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UNITED STATES OF AMERICA. 



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Vulcanite and Celluloid : 



INSTRUCTIONS IN THEIR PRACTICAL WORKING 



FOR 



DENTAL PURPOSES. 



BY 



S. ELDEED GILBERT, D.D.S., 

Instructor or Clinical Dentistry in the Philadelphia Dental College. 




PHILADELPHIA: 

The S. S. White Dental Manufacturing Co. 

1884. 



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Copyright. 

The S. S. White Dental Mfg. Co. 

1884. 



Press of Patterson & White. 



PREFACE. 



c\ 



The aim of the author in the production of this volume 
has been to present the subject-matter as concisely and 
plainly as possible, as the work is designed especially for 
the use of students. Practical hints upon the taking of 
impressions of the mouth are first given, and these are 
followed by a consideration of materials and processes, 
step by step, up to the completion of the case. 

The author desires to express his sense of obligation to 
Dr. J. W. White for valuable suggestions and for furnish- 
ing illustrations, as also to the Celluloid Manufacturing 
Co. and T. B. Welch & Son for esteemed favors. 

S. ELDRED GILBERT, 

1237 Arch Street. 

Philadelphia, Pa., 

February 4, 1884. 



VULCANITE. 



Vulcanite is the result of the combination of caoutchouc 
(India-rubber) with sulphur through the agency of high 
temperature. The earliest information on this subject is 
found in the specification of Charles G-oodyear, in 1844, 
for producing indurated rubber. His mixture consisted 
of caoutchouc, sulphur, and white lead. In 1855 he ob- 
tained a patent for the use of vulcanite as a base for arti- 
ficial dentures. The coloring matter used in red vulcanite 
is vermilion. Black vulcanite has no coloring, but consists 
of caoutchouc and sulphur, and this product, being nearly 
pure rubber, shrinks more than the colored vulcanite. 

Impressions of the Mouth. 

The mouth being in a proper condition, the initial step 
towards the construction of an artificial denture is the 
taking of an impression. One of four materials may be 
used for this purpose, — namely, gutta-percha, wax or a 
combination of wax and plaster, modelling composition, 
and plaster of Paris. 

Gutta-percha. — Gutta-percha is softened in hot water 
and placed in the impression cup ; then inserted into the 
mouth, and gently crowded into position, the cheeks and 
lips being pressed against it while so held, thus causing 



6 VULCANITE AND CELLULOID 

the softened material to take the form of the mouth. This 
is allowed to remain until hard enough to retain its form, 
and then removed and placed in cold water, after which 
plaster is poured into the impression and forms the cast. 

Wax. — This is manipulated similarly to gutta-percha, 
and may he heated either in hot water or hy dry heat. 
Care should be taken not to have it so hot as to run, as 
this injures its working properties. 

Wax and Plaster. — Many dentists prefer to use these 
combined, as follows : First obtain the impression in 
wax ; then cut away about one line of the wax covering 
the whole surface of the impression. Mix a thin batter 
of plaster, and place enough in the wax impression to 
nicely cover it. Replace it in the mouth and force it into 
position, allowing it to harden. When removed and 
varnished with shellac, a thin coating of soap may, if 
desired, be applied to the surface. Place the impression 
in water and allow it to absorb freely. The batter of 
plaster is then poured into the impression. This is pref- 
erable to oiling, as it prevents the formation of air-bubbles 
or the softening of the surface of the cast. The impres- 
sion and cast are as easily separated as where oil is used, 
and this mode is more advantageous in all impressions 
taken in plaster or plaster and wax. 

The following method is preferred for all plaster im- 
pressions, as it leaves the model with a dense polished 
surface : Stain the impression with thin shellac varnish. 
When dry, apply a thin coat of sandarac varnish, and after 
this is dry pour the plaster. The varnish is composed of 
gum sandarac dissolved in alcohol. 



FOR DENTAL PURPOSES. 7 

Modelling Composition. — "Next to plaster, this is probably 
the best material for impressions. To use it to the best 
advantage, water should be heated in a shallow vessel 
until it reaches the boiling point. It should then be 
removed from the flame and the composition placed in it, 
allowing it to remain until thoroughly softened, by which 
time the water will have lost some of its heat, and the 
material will not be too hot to handle when taken out 
of the water with the spatula. Pass the impression cup 
over a flame until it is heated sufficiently to prevent the 
hardening of the material when brought in contact with 
it. Build up the composition to approximate the form 
of the arch ; then proceed as with wax until the surface 
begins to harden slightly. Press it around the outside 
of the ridge, applying also a slight pressure with the 
index finger upward and forward to that part which 
overhangs the back of the tray. Allow it to cool still 
more, and at the end of another minute or so it may be 
carefully removed, caution being used not to draw in the 
sides by pressure against the corners of the mouth. 
Plunge the impression in cold water at once, letting it 
remain until hard. Before filling it with plaster wet the 
surface. A smooth, glossy model, with a clear repro- 
duction of each line in the mouth, will be the result. To 
remove the impression from the cast, heat the water as 
before; place the cast and impression in it until the 
compound is softened, when it is easily detached. In 
most cases No. 2 Modelling Composition will meet all the 
requirements. 

Plaster of Paris (Sulphate of Calcium). — This I consider to 



8 VULCANITE AND CELLULOID 

be superior to any of the other materials for taking impres- 
sions. All of the others draw more or less where there 
is an undercut, or where the teeth tip in different direc- 
tions. I am aware that plaster is not as easily manipu- 
lated nor as pleasant to the patient as a plastic material ; 
but most of this unpleasantness may be overcome, if the 
operator thoroughly understands the use of it and adapts 
himself to circumstances. When a correct plaster im- 
pression is obtained no guesswork is required, as is the 
case when a plastic material is used. Plaster fractures 
where there is a heavy undercut or where there are teeth. 
This is just what we want it to do, as the pieces, when 
properly placed together in the cup, form a correct im- 
pression of the mouth. These pieces are held in place 
by dropping a little melted wax upon them to attach them 
to the edge of the cup. 

Full Upper Impressions. 

For a full upper impression, select a cup a little larger 
than the mouth. If the palatine portion is high, the cup 
should be well raised in the center; if it is a flat mouth, 
the cup should be correspondingly flat. The edges should 
extend high or low, according to the amount of absorp- 
tion. To prevent the plaster extending too far back, 
build a rim of wax across the posterior edge of the cup. 
If the patient is easily nauseated, ask him to breathe 
through the nose ; to avoid swallowing, and to place the 
tongue against the impression tray or the fingers of the ope- 
rator as he holds it in position. It is sometimes necessary, 



FOR DENTAL PURPOSES. 



in cases of very sensitive mouths, to administer bromide of 
potassium half or three-quarters of an hour previous to 
taking the impression. This generally prevents retching, 
which it would be almost if not quite impossible to other- 
wise avoid. There are several ways of overcoming nausea, 
but I think it unnecessary to mention others, as the above 
will prevent it in most cases. The cup having been 
chosen, sprinkle the plaster in the bowl of water until 
it has taken it all up ; then stir it a little (if this is 
properly done there will be no air-bubbles). Fill the 
impression cup, being careful not to overload it. Dry 
the palatine portion of the mouth with a napkin, and 
place a little plaster in the highest part of the arch, 
working it into position with the index finger, excluding all 
air-bubbles. The cup and plaster are now gently forced 
into place, allowing the posterior portion to be pressed up 
slightly in advance of the anterior part. This forces the 
plaster where it is needed, namely, at the sides and in 
front. The head of the patient should be thrown for- 
ward, so that the chin rests nearly upon the chest. The 
cheeks and lips are pressed against the soft material, which 
is allowed to remain until the plaster in the bowl will 
break with a distinct fracture. To remove the impression 
from the mouth, wet the finger with water and raise the 
lips and cheeks from it. Should it fall when this is 
done, or be removable afterwards without any force, it 
should be discarded as imperfect. To have a perfect 
impression, it must cling to the mouth. This is one of 
the best tests, but it sometimes fails. Should the plaster 
set too slow, the setting may be hastened by sprinkling a 



10 VULCANITE AND CELLULOID 

few grains of sulphate of potassium or of salt in the water 
before mixing. Tepid water should be used, as it pro- 
motes the setting- Do not be satisfied until you obtain a 
perfect impression, for without this you cannot have a" 
perfect-fitting denture. 

Detaching the Upper Impression. — The lips being raised 
from the sides, press the handle of the cup up and then 

down. If this does not loosen it, ask the patient to give 

* 
a slight cough or puff by sending the breath out of the 

mouth quickly. In removing a case that has a heavy 

undercut at the anterior of the alveolar ridge, it should 

be drawn forward and downward at the same time. 

Full Lower Impressions. 

A cup should be selected that is best adapted to the 
case. Sometimes it is necessary to build wax around the 
rim, to have it deep enough ; at other times it will need 
trimming away. The plaster should extend well down 
on the inside of the ridge at the back, as this is to be 
depended upon to a great extent to hold the denture in 
place. Before forcing the plaster down, see that the 
cheeks do not fold in upon the ridges. This is prevented 
by pushing them out with the finger just as the plaster is 
in position, but before it is crowded into place. Have 
the patient raise the tongue ; then force the cup and con- 
tents gently down. The tongue should then be lowered,, 
thus crowding the material close to the ridge upon the 
inside. Press the cheeks against the plaster, and allow it 
to harden; after which raise the lips and cheeks away 



FOR DENTAL PURPOSES. 11 

from the cup, working the handle gently up and down 
until the impression loosens and may be removed from 
the mouth. 

Partial Upper Impressions. 

Where the mouth contains several teeth, an impression 
can be taken with greater ease by the following method, 
rather than by filling the cup with plaster : With the 
spatula place enough plaster against the palatine surface 
to fill the mouth even with the masticating edges of the 
teeth. If it is desirable to obtain a perfect imprint of the 
buccal and labial surfaces, place a little plaster against 
the inside of the rim of the cup. A perfect impression 
is thus obtained without a large excess of material. Pre- 
vious to inserting the cup a rim of wax is built across the 
posterior edge. It is then passed into the mouth beyond 
the plaster ; then drawn forward and gently pressed into 
place, causing the heel to go up in advance of the anterior 
part of the cup, thus forcing the surplus plaster out at 
the front and sides. 

Partial Lower Impressions. 

For a partial lower impression the cup should be deeper, 
but filled with plaster as for a full lower case. 

The following is an excellent method of taking impres- 
sions where the teeth are elongated and loose, or where 
they stand in different directions — as, for instance, where 
the incisors lean in, or a molar on one side tips forward 



12 VULCANITE AND CELLULOID 

and one on the opposite side backward. Although this 
is a difficult case, it may be satisfactorily overcome by 
first obtaining an impression in wax and then running a 
model in it. Wax caps are then fitted over the crowns 
of the plaster teeth, extending almost to the gums. This 
leaves all of the soft parts and necks of the teeth exposed, 
allowing an impression to be taken of them in plaster. 
Select a cup suitable for the case ; or one may be made so 
by building up the sides and lingual portions with wax. 
Remove the wax caps from the model and place them 
upon the natural teeth; then take the impression in 
plaster in the usual manner, removing it the same as in a 
full case. Replace the plaster that breaks away around 
the necks of the teeth in the impression, and then run 
the model. 

To Remove a Partial Impression. — Where there are no 
undercuts the impression may be removed as soon as the 
plaster will fracture without crushing ; but where there are 
undercuts or dovetails it should be allowed to set hard. 
The cup is then loosened and carefully removed, leaving 
the plaster in the mouth. With a pair of foil-pliers 
remove the wax and any of the plaster that may have 
been forced over it. This leaves the posterior part of the 
mouth free. With a thin-bladed knife cut a line through 
the plaster down to the masticating surfaces of the teeth, 
and where teeth are absent cut a little deeper. Cut a 
line over and down to the cuspids upon the labial surface. 
Insert the knife-blade in the line cut over the teeth upon 
one side, and by twisting it the plaster will fracture to 
the line opposite the cuspid. The piece thus secured is 



FOR DENTAL PURPOSES. 13 

removed. Then the opposite side and front are treated 
in the same manner. Should the palatal portion be held 
fast by the molars tipping in and forming a dovetail, cut 
a line with the knife about a quarter of an inch from the 
teeth and nearly through to the hard palate, beginning 
back and coming forward to the cuspid ; place the knife- 
blade in the crevice and twist enough to fracture the 
plaster, when it may be easily removed. If there are 
pieces still remaining between the teeth, which prevent 
the removal, of the body of the plaster, they are to be frac- 
tured with the knife and taken away laterally. After the 
plaster covering the palatine portion is removed, place the 
pieces together in the cup and fasten them with wax. If 
all of the pieces are put in their proper places, the im- 
pression will be found correct, if care has been taken to 
force the plaster into place in the mouth. For removing 
the body of the plaster use a small, flattened instrument, 
bent at an acute angle. This is inserted between the 
plaster and palate and drawn gently down, when the 
plaster loosens and is easily taken out. Yarnish and pro- 
ceed as with a full upper impression. 

In removing a partial lower impression, the cup is 
detached, leaving the plaster in the mouth. A line is 
then cut over the teeth after the manner described in the 
upper case. The knife-blade is inserted in this line and 
the plaster broken from each side and in front, that 
remaining on the inside of the teeth being pressed in 
with the finger, when it fractures and falls away. With 
practice, many little devices will be found for removing 
all partial impressions. 



14 vulcanite and celluloid 

Breaking Teeth from the Model. 

To prevent the breaking of teeth from the plaster 
model, insert small pieces of wire or pins in the impres- 
sion made by the teeth before running the cast. 

Plaster Casts. 

For all laboratory work strong plaster should be used. 
That which is moderately coarse is the best, as it is 
hard and tough when thoroughly set. Its expansion is 
greatest when mixed thin, and, therefore, better casts are 
obtained where the plaster is mixed as thick as it may be 
and work well. 

Treat the surface of the impression as before directed. 
The following is about the right consistence for the var- 
nish : 

R • — Shellac, 5 ii ; 
Alcohol, ^ i. 

Allow this to stand until the shellac is dissolved. After 
varnishing the impression, place it in water until thor- 
oughly saturated, which may be known by bubbles ceas- 
ing to rise. The impression parts from the cast as readily 
as when oiled, and as in this method no oil is used, its dis- 
advantages are avoided. Remove the impression from 
the water and fill it with plaster, gently tapping it to 
force out all air-bubbles. Build the material up about 
half an inch, and level it off. When hard the impres- 
sion must be carefully removed by cutting it down and 
breaking it off, piece by piece, until the cast is free. 



FOR DENTAL PURPOSES. 15 

The Articulation. 

For a full upper denture on vulcanite a base plate is 
required. This may be made of wax, gutta-percha, par- 
acrine and wax, or modelling composition, the last being 
preferable. These are warmed and shaped to the cast, and 
a piece of softened wax is made into a roll and placed 
upon this base plate and over the alveolar ridge, to take the 
place of the teeth, shaping it so that it will assume the gen- 
eral form of the arch. This is then tried in the mouth, 
and, if too long or too short, trimmed or added to as may 
be required ; the wax being placed so that it will restore 
the contour as near as possible. This is one of the most 
important points for beginners, and, I think, one of the 
most difficult, for, unless care is exercised, the bite will 
be made too long or too short, causing the teeth to be 
correspondingly so ; but some trouble may be avoided by 
cutting one or more blocks of soft pine, about half an 
inch square and thicker than the required bite, and 
securing them to the base plate with melted wax at 
points opposite to the occluding teeth. Let the grain of 
the wood run parallel to the ridge. With a knife split 
off small portions until the proper length is reached. 
The wax may be applied and the patient may close the 
mouth without danger of going beyond the distance 
established by the blocks. 

Length of the Teeth. 

When in the mouth, and the upper lip is at rest in its 
natural position, the wax should be about one-sixteenth 



16 VULCANITE AND CELLULOID 

of an inch longer than the lip for the upper and about 
one-sixteenth shorter than the lip for the lower bite. 
Always mark the median line in the articulation. The 
wax should be heated a little od the biting surface ; then 
placed in the mouth, and the patient requested to close 
the teeth upon it just hard enough to give an imprint of 
their ends. Patients should never be asked to bite 
naturally, as they will in that case do just the opposite in 
their effort to have it right. They will throw the chin 
out or bite sidewise, thus giving the wrong articulation. 
A good method is to tell them that you wish to try the 
wax and ascertain the length of the teeth. Then place it 
in the mouth and request them to hold it in position with 
the teeth. Remove and trim it, and then replace it in 
the mouth again, with the same instructions to the 
patient as before. The author does this several times while 
taking the articulation, each time observing where the teeth 
closed, before a satisfactory result has been reached. 
When the closure has been the same each time, the 
articulation will be found to be correct, and the patient 
can be instructed to close a little harder, which he does 
without an effort, thus giving the correct articulation. 
But sometimes this will not do, and different methods 
have to be resorted to. "When this fails, the patient may 
be requested to swallow and to hold the teeth where they 
closed in swallowing, or to sit upright, and the operator 
may place one hand between the shoulders and with the 
other push the head back, bending the neck as short as 
possible. The mouth being open, request the patient to 
close it. Another very good method is to engage the 



FOR DENTAL PURPOSES. It 

patient in conversation while the wax is in the mouth, and, 
watching the articulation, when he is off his guard, ^ 1 
suddenly catch the jaw in the hand and hold it just 
where he closed in talking, forcing the teeth into 
the wax as desired. For a full upper and lower 
impression, trim both pieces of wax as the case 
may require, and, softening the edges of each, 
place them in the mouth. When a correct clos- 
ure is obtained, mark the median line above and 
below, and also cut lines in the wax at the sides, 
so that, in case the sections become separated in 
removing them from the mouth, they may be 
easily placed in position ; or fasten the parts to- 
gether in the mouth with double-pointed tacks. 

The Articulating Model. 

For a full upper or lower case, the Avax articu- 
lation is placed upon the cast and fastened by 
running a hot spatula (Fig. 1) around the edges. 
If a metal articulator is used, the cast is fastened 
to this with plaster. Fill the cavities made in the 
wax by the teeth with water, and add a little plas- 
ter, mixed thin. By jarring, this takes the place 
of the water, leaving each tooth perfect. Fill 
enough plaster upon this to bring it even with the 
top or bottom of the articulator, as the case may 
be. Smooth this and allow it to harden, after 
which separate and remove the wax, laying it 
aside to be used as a guide in restoring the contour. The 

2 



18 VULCANITE AND CELLULOID 

base plate is then fastened to the cast and the teeth ar- 
ranged upon it. 

The following method of obtaining a more complete 
articulating cast of the opposing teeth may be employed : 
An impression is obtained (in either wax or modelling 
composition) of the jaw opposite to the one that the teeth 
are to be made for, and a plaster cast is run in it. When 
the cast becomes hard and has been separated from the 
impression, the teeth upon it are inserted into the depres- 
sions made in the wax articulation by the natural teeth, 
and fastened by running a hot spatula around them. 
Both casts and articulation are fastened in the articulator 
with plaster and allowed to stand until hard, after which 
the base plate and teeth are arranged as in the first method. 

It will be seen that by this mode we have a full cast 
of both jaws with all the opposing teeth and soft parts as 
they are in the mouth. In the first we have only the 
ends of the teeth of the opposing jaw. 

Selecting the Teeth. 

To make a proper selection, the temperament should 
be studied. The teeth should harmonize in shape, size, 
and color with the sex, age, and peculiarities of the 
patient. Artificial teeth should never be as large for a 
full denture as the natural ones, as they appear much 
larger when in the mouth. The arch becoming con- 
tracted by absorption, renders a corresponding reduction 
in the substitutes necessary. 

In arranging teeth in position, bear in mind that there 
are three temperaments in which the six oral or front teeth 



FOR DENTAL PURPOSES. 19 

form nearly the arc of a circle — namely, the nervous, 
bilious, and lymphatic. The outside or buccal cusps of 
bicuspids and molars are almost upon a line with the 
most prominent part of the cuspid when looking at the 
case from the front. Where the denture is set up in 
this way the bicuspids will not be prominent, as they 
drop slightly behind the cuspids. In using sectional 
teeth, it will be found that the edges of the gums do not 
harmonize between the cuspids and first bicuspids. This 
form of arch is preferable in the temperaments mentioned 
to that of the horseshoe, which shows the bicuspids and 
molars as the patient opens the mouth. The uneven 
jointing of the gums spoken of may be overcome by 
grinding the posterior edge of the front block down 
slightly with a corundum wheel; then polishing with a 
felt- wheel and pumice, revolving it rapidly. This should 
be done before the teeth are fastened in place, and not 
after the plate is finished. 

Cases of the fourth or sanguine temperament, or where 
it predominates, present a horseshoe arch, the bicuspids 
being thrown well out. People of this temperament 
seldom have to resort to the use of an artificial denture, 
as they generally retain their teeth until they are worn 
almost to the gums before they give much trouble. 

In block teeth the gums should be ground squarely 
together. When this is done, make a small Y-shaped 
space upon the inside of the block, and then replace 

them. 

Waxing up the Case. 

When the teeth are properly arranged upon the model, 



20 VULCANITE AND CELLULOID 

flow wax around them with the spatula, being careful 
that it does not enter the joints. This wax trial plate 
should be made as nearly like the vulcanite plate as 
possible. The articulation may be tested by placing this 
plate in the mouth. The wax should be made smooth 
with either a blowpipe flame, chip-syringe, or a cloth 
moistened with benzine. The case should now be de- 
tached from the articulator and flasked. 

Fig. 2. 





mm 

Old Style. 

MM f 



■L , 



New Style 

Casting the Plaster Mold. 

Either of the flasks illustrated in Fig. 2 will be found 
to meet all requirements, and they are used more exten- 
sively than any others. The casting of the mold is done 
by placing the cast with the teeth upon it in the flask. 
Before doing so, however, saturate the cast with water to 
prevent its robbing the new plaster of moisture. Mix 
the batter as thick as it will bear, and pour, partly fill- 
ing the lower section ; then place the cast and teeth in it 
bottom down (as shown in Fig. 3) and slightly inclined at 
the anterior portion. This excludes all air-bubbles when 
it is forced down into place. The plaster should extend 
up to the wax (Fig. 3). Here the dividing line is made 



FOR DENTAL PURPOSES. 



21 



between the two sections. This allows the teeth to be 
imbedded in the upper section of the flask. 

Where plain teeth are used, without any rubber over 
the anterior part of the alveolar ridge, and the teeth 
are resting directly upon the gum, the division should 
be at their cutting edges, thus fastening them in the 
lower section, with their bases upon the cast. After the 
plaster has set, trim it smooth and varnish with shellac, 

Fig. 3. 




being careful not to get any upon the teeth or gums. 
Place the ring forming the upper section accurately upon 
the lower ring, and see that there is no plaster between 
them. Set the lower section in water, allowing it to 
take up all it will. (Oil may be used in place of water, 
if desired, but only the surface which has been varnished 
should be oiled, — not the teeth or gums.) Then mix the 
plaster as for an impression ; remove the flask from the 
water, and pour in the material, gently tapping it to force 



22 VULCANITE AND CELLULOID 

out air-bubbles. When full, put the top on and press it 
down. The case is now set aside until hard. 

Separating the Flask. 

Before the flask is separated it should be warmed to 
soften the wax, but not enough to melt it. This is 
accomplished with either wet or dry heat, but wet is pre- 
ferred, as dry is more liable to melt the wax, causing it 
to combine with the plaster ; or, if gutta-percha is used, 
it will adhere to the cast if made too hot, making it 
difficult to remove. In case the wax melts and runs into 
the plaster, the difficulty may be partly overcome by 
covering the flask (face upwards) with boiling water, and 
allowing it to stand for a few minutes. Where wet heat 
is used, in the following manner, it will prove very satis- 
factory : Set the flask in a vessel of water, and heat it to 
about 135° F. when gutta-percha is used; 120° F. where 
wax or wax and parafline are used. The flask should 
remain in the water a few minutes at this temperature, so 
that the heat may permeate all parts of the mold ; then 
•remove it, and the flask will readily separate, bringing 
the model plate away from the teeth. In case it should 
accidentally become too warm, immerse it in cold water a 
moment. This will chill the surface of the wax, when it 
may be easily removed. 

Preparing the Mold for the Eubber. 

When the flask is opened the model plate is taken 
from the mold. A medium-sized hatchet excavator may 



FOR DENTAL PURPOSES. 16 

be used for removing the wax from around the pins. 
This being done, it will be found that some still remains. 
This is washed out by pouring a stream of boiling water 
upon it, allowing it to fall about a foot, striking upon the 
parts of the mold containing the pieces of wax. If 
gutta-percha is used, it will be necessary to remove it 
with the instrument, not using hot water. It is impor- 



Fig. 4. 




tant that ail the wax be removed, as rubber loses its 
integrity when it comes in contact with it. We are now 
ready for cutting the grooves, or waste gates, which are 
made for the purpose of allowing the excess of rubber to 
flow in when the flask is being closed. They should be 



24 VULCANITE AND CELLULOID 

cut in the plaster, radiating from the cast to the edge of the 
flask. Fig. 4 represents this section prepared for packing. 

« 
Coating the Mold. 

The mold should be covered with some substance to 
prevent the rubber from penetrating and adhering to it, 
and leaving the plate rough. Either liquid silex, collo- 
dion, or tin-foil may be used for this purpose. 

Liquid Silex (Silicate of Soda). — This will prevent the 
rubber from adhering to the model during the process 
of vulcanizing, and is easily removed from the surface of 
the plate in finishing. A thin coat of this should be 
applied to the model with a small, soft brush before 
allowing it to dry. "Wipe off all that will come away. 
This prevents the thick, white scale of dry silex from 
forming on the inside of the plate, as it will when a 
heavy coat is allowed to dry on the cast. In case any of 
the scale of silex is on the plate, it may be removed with 
a stiff brush-wheel and wet pumice. Should the liquid 
become thick by standing, it may be thinned with water. 

Tin-Foil. — When this is used the mold should be 
coated with shellac varnish, and while it is still adhesive 
the tin-foil should be carefully pressed upon it wherever 
the rubber plate touches the cast. This being done, 
coat the tin with collodion, allowing it to dry; then 
soap it thoroughly. After the case is vulcanized the tin 
may be peeled off, leaving a polished surface upon the 
inside of the case. 

Collodion. — This works very well, and is used similarly 
to liquid silex. 



FOR DENTAL PURPOSES. 

To Fasten Loose Teeth. 

Sometimes, upon opening the flask, a block 
or a single tooth becomes loosened. When this 
occurs, place a drop of liquid silex or collodion 
where the tooth belongs, and force it into po- 
sition. Allow it to stand for a short time until 
the silex or collodion becomes dry, and it will 
be held firmly in place. 

Packing the Case. 

After the case is separated, and before pack- 
ing the rubber, fill the space before mentioned 
with oxy chloride of zinc, oxyphosphate, or plas- 
ter. When this is hard, pack the case. The 
joints, if perfectly ground, will come out with- 
out dark lines, unless poor plaster is used, or 
there has been too great an excess of rubber, 
causing the blocks to move. As a further pre- 
ventive, a narrow strip of pink rubber may be 
placed behind each joint, tucking it in below 
the pins and above the upper edge of the blocks. 
All the instruments needed for this purpose are 
those represented by Fig. 5. The smaller one 
of the two may be made from an excavator, 
blunt at the point, and turned at a right angle. 
It is necessary to have the hands and instru- 
ments clean when packing a case, as any foreign 
substance injures the rubber either in texture 
or color. In packing, it is best to have the 



25 



Fig. 5. 



26 



VULCANITE AND CELLUOLID 



mold warm, as it works much better ; yet this is not im- 
portant, as with cold molds and heated rubber the same 
results are obtainable. 

The rubber works best when cut into different-sized 
pieces. A large piece the shape of the palate may be 
cut, and also several small ones. Moist heat is preferred 
for softening rubber, as dry heat is liable to injure it by 
overheating. Fig. 6 represents a vessel for heating rubber 

Fig. 6. 




for packing. The material is softened by laying it upon 
the cover ; or the boiler of the vulcanizer may be used, 
covering it with an earthen plate, on which the rubber 
to be softened may be placed. These are also convenient 
for heating the flasks before bringing them together, as 
the water is boiling and ready to receive them as soon as 
they are packed. 

"When the rubber is softened, pack it into place in the 
mold, using the large pieces where they are required, 



FOR DENTAL PURPOSES. 27 

and consolidating each piece as it is added, being careful 
to exclude any particles of plaster. The piece cut for the 
palatal portion should be pressed into position with the 
thumb and fingers, first wetting them. Should more 
rubber than this piece be required, it may be packed 
upon the other, as it will now into place when heated. 
Care should be used not to pack the case too full against 
the gums, particularly when they are thin and come close 
to the cast when the flask is closed, as in such case the 
force of bringing it together crowds the rubber against 
the porcelain blocks and is liable to fracture them. If 
left thick in the center, the force is greatest upon the 
strongest part of the mold, and as the rubber yields it 
will flow in and around the frail parts without injuring 
the thinly-ground gums. 

Amount of Eubber Required to Fill the Mold. 

Rules are given to ascertain by weight and measure 
how much rubber it will require for each case. The 
most practical way is by displacement, and is as follows : 
Upon removing the model plate, place it in a glass vessel 
and cover it with water, marking the rise ; remove and 
add rubber until the water reaches the same point. Fig. 
7 represents a very simple and useful gauge for this pur- 
pose. 

With the screw, set the lower point to the level of the 
water in the glass ; then throw in the model plate, and set 
the upper point to the then level of the water. The glass is 
now emptied, and rinsed to rid it of all foreign substances 



28 



VULCANITE AND CELLULOID 



liable to mix with the rubber ; then again fill the glass to 
the lower point with water, and add enough rubber to 
cause the water to rise to the upper point, which will 

Fig. 7. 




be just enough to fill the mold. If desired, a little sur- 
plus may be added. 

Closing the Flask. 

The case having been packed, the sections of the flask 



FOR DENTAL PURPOSES. 



29 



are placed together and closed, either by a clamp or screw 
bolts. 

Rubber is of a yielding nature, but if pressure is ap- 
plied suddenly, before it is heated, there is great liability 
of fracturing the cast or teeth. One of the best of the 
devices that have come under my notice for closing a 
flask is Welch's automatic flask press. (Fig. 8.) 



Pig. 8. 




The flask is placed in this, and the clamp screwed 
down and put into a vessel of water, where it is allowed 
to stand for a short time and boil, when it will be found 
to be closed. The screws may now be put in to hold it 
in place while vulcanizing. If screw bolts are used for 
closing the flask, they should be turned only as far as can 
be done with the fingers. The case is then put into boil- 
ing water and allowed to heat for a few minutes ; then 
remove and gently turn each screw, giving time between 



30 VULCANITE AND CELLULOID 

the turns for the rubber to run. As soon as it requires 
force to turn the screws, heat it again, and so continue 
until the flask is closed. Dry heat may be used, but there 
is danger of injuring the rubber by overheating. 

Vulcanizing. 

A high degree of heat is required to vulcanize rubber. 
This is maintained for a longer or shorter period, in ac- 
cordance with the temperature. As a medium, hot air, 
hot water, or steam may be employed. Water or steam, 
confined 'in a steam-tight vessel called a vulcanizer, is 
most commonly employed for this purpose. (See Fig. 9.) 

The vulcanizer generally has a single chamber. The 
ilask is covered with water ; then allowed to heat gradu- 
ally, from thirty to forty-live minutes being necessary be- 
fore the required heat for vulcanizing is obtained, and the 
thicker the plate the longer it should be in attaining this 
point. 

The " New-Mode " vulcanizer will be considered under 
the head of celluloid apparatus. 

Elastic Force of Steam. — Prof. "Wildman writes with 
reference to this subject as follows : 

" As high steam is used in vulcanizing, it is important 
that the operator should be conversant with the nature 
of the agent which he employs to accomplish his end. It 
is perfectly safe ; but the following will show him that it 
must be used with discretion and judgment. Numerous 
experiments have been made by scientific men to ascertain 
the elastic force of steam at different temperatures. The 



FOR DENTAL PURPOSES. 



31 



Fig. 9. 
Whitney Vuleanizers. 





For Alcohol and Gas. 



For Kerosene. 



Hayes Vuleanizers. 





32 VULCANITE AND CELLULOID 

results of their investigations are not uniform ; although 
they agree in showing the immense force exerted hy this 
agent at high temperatures. Has well's tables are looked 
upon as authority. The results of the investigations of 
the Franklin Institute Committee, in the higher degrees, 
give a greater elastic force than the table below quoted. 
I shall, however, quote the results of the experiments of 
the commission of the French Academy appointed by 
the French Government to investigate this subject, for 
the reasons that, from the manner in which they were 
conducted, they are probably as reliable as any, and that 
they are extended to a more elevated temperature than 
the others. 

Elasticity of steam, p 

taking atmospheric Temperature, F. squaTrndif lbs. 

pressure as unity. u ' 

1 212° 14.7 

1£ , 233.96° 22.05 

2 250.52° 29.4 

1\ 263.84° 36.75 

3 275.18° 44.1 

3£ 285.08° 51.45 

4 293.72° 58.8 

4£ 300.28° 66.15 

5 307.05° 73.5 

h\ 314.24° 80.85 

6 320.36° 88.2 

6£ 326.26° 95.55 

7 331.70° 102.9 

7£ 336.86° 110.85 

8 341.78° 117.6 

9 ,350.78° 132.3 

10 358.88° 147 



FOR DENTAL PURPOSES. 33 

Elasticity of steam, Pressure per 

taking atmospheric Temperature, F. square inch, lbs. 

pressure as unity. 

11 366.85° 161.7 

12 374° 176.4 

13 380.66° 191.1 

14 386.94° 205.8 

15 392.86° 220.5 

16 398.48° 235.2 

17 403.82° 249.9 

18 408.92° 264.6 

19 413.78° 279.3 

20 418.46° 294 

" I would here call the attention of those using high 
steam to an important consideration. In raising steam, 
the ratio of increase of pressure or elastic force is far greater 
than that of the increase of temperature. 

" By referring to the above table, commencing at 212° 
and taking steps as near fifty degrees as is given in the 
ascending scale, we find this exemplified; thus, — 

Increase of Increase of force Giving a force 
Temperature. per sq. inch per sq. inch. 

From 212° to 263.84° = 51.84° 22.05 lbs 36.75 lbs. 

" 363.84° to 314.24° = 50.40° 44.10 lbs 80.85 lbs. 

" 314.24° to 366.85° = 52.61° 80.85 lbs 161.85 lbs. 

" 366.85° to 418.46° = 51.61° 132.15 lbs 294. lbs. 

" This comparison shows clearly how rapidly the pres- 
sure increases at high temperatures, and warns the opera- 
tor that a strong instrument combined with care and 
judgment in its treatment are indispensable to safety. 
Besides the rapid increase of pressure, it must be borne 

in mind that, at high temperatures, copper, of which the 

3 



34 VULCANITE AND CELLULOID 

boiler is composed, becomes weakened, and in a meas- 
ure loses its power to resist tbis great imprisoned force. 
Copper in passing 212° to 320° F. loses about one-tentb 
of its strength, and at 550° it has lost one-fourth of its 
tenacity." 

When using a vulcanizer or rubber for the first time 
it is always better to employ a test piece. Invest a piece 
of rubber in plaster covered with tin-foil, and place it 
beside the flask. Wben the vulcanizer is opened, remove 
the plaster from the test piece, and if it is of the right 
hardness, upon scraping it will give a shaving like that 
of born; if too soft, it will not be springy, and when 
bent will remain so; if too hard, the shaving will be 
brittle and crisp and the rubber dark. In case it is not 
vulcanized enough, reclose the vulcanizer, and continue 
the process for a time, in accordance with the indications 
of the test piece. Place the flask in the vulcanizer and 
fill it two-thirds full of water ; this allows space for the 
steam, with less liability of blowing out the safety disk 
before 320° is reached. Dust a little black-lead, soap- 
stone, or whiting over the packing. This prevents stick- 
ing and the escape of steam in case the packing is imper- 
fect. Replace the cap and screw down firmly. The heat 
is now applied, for which gas, alcohol, or coal-oil may be 
employed. Yulcanizers are generally constructed so that 
either gas or coal-oil may be used. The flame should be 
so regulated that it will not deposit carbon, for this acts 
as a non-conductor, and in a measure delays the heating 
of the case. It should be gradually raised to 320° F., and 
this sbould not occupy less than half an hour. If the piece 



FOR DENTAL PURPOSES. 35 

is thick, an hour will not be too long, for when heated 
too rapidly the case is sure to he spongy or porous. 
When the vulcanizing point (320° F.) is reached, the 
flame should he so regulated that the temperature will 
remain stationary at that point until the case is finished. 
The operator should always be watchful, as neglect will 
not only ruin the case, but greatly endanger life. 

The length of time for vulcanizing varies with the dif- 
ferent varieties of rubber, ranging from fifteen minutes 
to an hour and a half. The time is usually stated upon 
the package, but it is best to use a test piece, as ther- 
mometers vary. "Where the heat is carried too high, the 
rubber becomes dark and brittle. This injures it for den- 
tal purposes. What has been written applies to red rub- 
ber. When black rubber is used, care should be exer- 
cised in raising the heat, especially when the piece is 
thick. After it has reached 320° F. it will vulcanize 
in the same time as the red, but it is considered 
best to use a lower heat and longer time. Black rubber 
has greater strength and toughness than the others. In 
using pink rubbers, the heat may be raised more rapidly, 
as they contain more foreign matter, and have very little 
strength. They are unfit for the entire plate, but may be 
used for gums in connection with other rubber. When 
employed in this way, the same time and care are re- 
quired as with the base alone. 

To attain the best results in hardening rubber, the heat 
should be gradually raised to the vulcanizing point, and 
not higher than 320° F. When vulcanized, turn off the 
flame and allow the case to stand until cold ; or, should 



36 VULCANITE AND CELLULOID 

the operator prefer, to facilitate the cooling, he may allow 
it to stand a few minutes, replace the thermometer cap, 
and plunge the vulcanizer into cold water. Then unscrew 
the top and remove the flasks, which must not be opened 
until thoroughly cold, as there is great danger of springing 
the plate. No harm is done by this process unless the water 
is allowed to cover the thermometer, in which case it is 
liable to separate the column of mercury. 

Opening the Flask. 

When the flask is cold, remove the top and carefully 
separate the remaining parts. With a pointed knife re- 
move the plaster near the margin of the flask ; after which 
gently tap the flask with a hammer, and the plaster will 
separate, being easily removed from the rubber with water 
and a stiff hand-brush. If the mold has been coated as 
directed, the case is now ready to finish. Before going 
further, however, the flasks should be thoroughly cleaned, 
in order to leave them in good condition for future use. 

Finishing the Case. 

Files and scrapers of different designs are required for 
this work. After filing the case into form, the scrapers 
are used for smoothing it and reaching any points not 
accessible to the file. 

The palatal surface should be made smooth and even. 
With a graver cut away the excess of material around 
the teeth. Some prefer coarse-cutting lathe-burs for 
dressing the plate down. When using these care should 



FOR DENTAL PURPOSES. 



37 



be exercised to prevent cutting through the plate. To 
avoid this mishap, use the callipers from time to time 
(Fig. 10) to ascertain its thickness. 

When the plate is of the desired thickness, it is made 
smooth with fine sand-paper. Then use powdered pumice 

Fig. 10. 




made into a paste with water. This may be employed 
by means of any of the following appliances revolved 
in the lathe : cork turned into a cone shape, sole leather 
cut into different sized wheels, and felt cones or wheels. 
After removing the scratches, the case is polished with a 
soft brush-wheel and prepared chalk made into a paste 
with water. Any inaccessible places not reached by the 



38 VULCANITE AND CELLULOID 

above means may be burnished with a steel burnisher. 
The part of the plate next to the mouth must not be 
changed, as it will injure its perfect adaptation. It may, 
however, be polished with a stiff brush- wheel and pumice 
without damage. Dress the posterior edge of the upper 
plate down thin. Do not leave the edges sharp, but round 
them to prevent cutting the tissues in case the plate ex- 
tends too far up on the sides and front. (This applies to 
both upper and lower dentures.) 

The perfect fit of a plate may be destroyed by allowing 
it to extend too far back upon the soft palate. If the 
case has no suction, and all previous steps have been 
correct, it is well to ascertain that it does not extend too 
far up, or that the muscles do not prevent its going into 
place. 

Mouths with a Hard or Bony Kidge in the Center. 

There is often trouble about plates fitting such mouths, 
particularly where the ridge extends far back. These 
cases are generally overcome by using a shallow, oblong 
air-chamber, which incloses all of the hard part, and only 
deep enough to prevent rocking. 

Partial Dentures. 

The general instructions for constructing a full denture 
will apply to the mode of procedure for making partial 
cases. If there are but few teeth to be supplied, the 
articulation may be taken by softening a piece of wax 
and forming it into a roll. Place this upon the remaining 
teeth, crowding it up against the parts where the teeth 



FOR DENTAL PURPOSES. 39 

are to be inserted and over the crowns of the remaining 
ones. Direct the patient to close the jaws ; press the wax 
around the teeth, and when partly hardened remove and 
cool it with water, afterwards replacing it in the mouth to 
test its accuracy. The cast is now run, and the wax 
articulation placed upon it. This is fastened to the brass 
articulator, or to one made of plaster. The plaster is now 
poured into the other part of the wax articulation (or an 
impression may be taken of the opposite jaw, as before 
directed). When it is hard, the wax is removed and the 
teeth ground to fit close to the gums. If plain teeth 
are used, a little is scraped away from the cast where 
they touch the plaster, in order to insure their fitting 
close to the natural gums. If desirable, they may be 
tried in the mouth while on the wax, and, if correct, 
replaced upon the cast, fastening in place with heated 
wax; after which invest them in plaster, allowing it to 
cover the cutting edges of the teeth that have no wax 
above them, so that in separating they are not moved. 
When there is a narrow neck of rubber extending 
out from the plate to a single tooth, it should have 
additional thickness to prevent its being broken off. 
In partial lower cases, where the front teeth are left stand- 
ing, a piece of metal should be imbedded in the rubber 
to stiffen and prevent the plate from being easily broken. 

Vulcanite Plates without Pressure. 

These are more especially designed for cases where the 
porcelain gums have to be ground so thin that they would 



40 VULCANITE AND CELLULOID 

be liable to fracture upon bringing the flask together in 
the common way. They may be used in any case, if de- 
sired, and are often preferable in partial sets. 

Proceed in the usual manner until the teeth are ground 
and articulated in the mouth on a trial plate (if one is 
used) ; then replace them upon the cast, filling the pala- 
tine portion to the articulating edges of the teeth with a 
solid mass of wax, using care not to displace the teeth. 
Remove one central block, taking out what wax there is 
under the gum, being careful not to remove any that is 
against the tooth or pins. Paint a thin coat of liquid 
rubber upon the cast where the wax has been removed. 
The rubber should be cut into small pieces, and well 
softened with heat. This is packed so that it takes the 
place of the wax. This done, replace the block, seeing 
that it goes into place the same as before it was removed. 
Take each block off separately, and replace the wax with 
rubber until it is packed solidly under each block ; then 
paint the cast above the porcelain gum with liquid rubber 
as far as the vulcanite is to extend. Having packed what 
rubber is required outside and above the porcelain blocks, 
the case may be partly flasked. Place enough plaster in 
one half of the flask to extend over the gums and tops of 
the teeth. Then the cast is forced down into the flask, and 
the plaster made smooth and even with the articulating 
surfaces of the teeth. When hard, remove the wax from 
the palatine portion of the cast. Should particles of wax 
adhere to the pins and about the teeth, remove it by 
pouring boiling water upon the case. Finish packing, 
first painting, with a thin coat of liquid rubber, the teeth 



FOR DENTAL PURPOSES. 41 

and cast where the vulcanite is to extend. Then pack 
small pieces of warm rubber solidly under the teeth and 
pins. Cut a piece of rubber large enough to cover the 
palatal portion. Warm this and press it firmly into place 
with the fingers, wetting them to prevent sticking. Finish 
flasking, and place the case in the vulcanizer. It should 
always be borne in mind that the plate comes out vulcan- 
ized as it is packed, and, if care is used to have it smooth, 
the case will be the same when vulcanized. When 
uneven, the surface is smoothed with a hot spatula 
before being flasked. In packing a case in this manner, 
pink rubber may be used with black or any other colored 
rubber, and the operator may know that it will stay just 
where it is packed and not become displaced, as when 
pressure is used. 

There is very little danger of its being porous when 
made in this manner, if packed and vulcanized with care. 
Each piece of rubber must be made solid before it is left. 

Metallic Clasps attached to Vulcanite Plates. 

There are cases where it is either impossible or not 
desirable to use atmospheric pressure for the retention 
of a partial denture. For cases of this kind clasps of 
metal are desirable, and to construct them properly Prof. 
Wildman gives the following instructions : 

" When made of metal, it must be either gold or gold 
alloyed with platinum. Silver will not answer, as rubber 
will not vulcanize hard in contact with this metal. First 
bend the clasp to fit the tooth accurately ; then make the 



42 



VULCANITE AND CELLULOID 



Fig. 11. 



attachment by which it is to be held to the rubber (this 
may be done by soldering a thin plate of gold or platinum 
to the clasp in such a position that it will be inclosed in 
the rubber); then perforate the plate with numerous 
holes, which should be countersunk on both sides. This 
plate entering the base, the rubber filling the holes forms 
pins which rivet the clasp securely to the rubber plate 
(see Fig. 11). 

" Or the attachment may be made in this manner : On 
the parts of the clasp that can be covered with 
rubber drill one, two, or three holes, as the 
space may admit ; insert gold or platinum wire ; 
solder with gold solder; then cut off at the 
proper length and head them. These act in 
retaining the clasp in the same manner as the 
double-headed pins in securing the tooth to the 
base, and afford the advantage over the perfo- 
rated plate of being more easily manipulated 
and less liable to become displaced in pack- 
ing the mold. The clasp is to be attached to the model 
plate, and will remain secured in the mold when it is 
opened" (see Fig. 12). 




Fig. 12. 




Plate Teeth For Vulcanite Work. 



An ordinary metal plate tooth may be used with rubber 
by soldering a narrow strip of gold or platinum plate to 
the ends of the pins : this, being imbedded in the rubber, 
renders it very secure. A narrow strip of rubber extend- 
ing to a single tooth may be strengthened by allowing the 



FOR DENTAL PURPOSES. 43 

gold strip perforated with holes and roughened on the 
edges to pass some distance into the rubber. 

Instead of forming the loop as mentioned, it will be 
preferable in many cases to punch holes in the strip for 
the pins to go through, and solder the piece close to the 
tooth, dressing the pins even with the surface of the 
metal strip, the same as in metal plate work. The piece 
soldered to the tooth should be bent so that it will extend 
into the rubber for some distance, and perforated with 
holes. Solder may be flowed over the strip at the angle 
to strengthen it. The rubber may be cut away, leaving 
nothing but the piece of gold and sub-lining of rubber 
at the base of the tooth. This method is employed with 
great advantage in cases where, upon closing the jaws, 
the points of the opposing teeth close nearly to the gums. 
This also permits of the use of a very thin tooth, which is 
often required in cases closing far up, and almost if not 
quite touching the opposing teeth. 

Kepairing. 

The method usually given in the books is simply for 
the repair of a tooth or block, and is as follows : If a 
tooth or block has been broken, or any change is to be 
made in the position of either, the teeth or fragments 
thereof are removed, and an irregular-shaped groove or 
dovetail formed in the base, occupying the space to be 
supplied. Into this space the tooth or teeth are perfectly 
arranged and supported with wax, filling the dovetail 
with the same, and giving additional fullness to compen- 



44 VULCANITE AND CELLULOID 

sate for waste in finishing. All portions of the piece, 
except the lingual face of the plate and teeth, are then 
imbedded in the lower section of the flask. The upper 
section of the mold is obtained in the usual way. When 
separated and all traces of wax are removed, the rubber is 
packed into the cavity around the tooth or teeth. Grooves 
are then cut, extending out from the mold ; the two sec- 
tions are heated and forced together, and the process of 
vulcanizing conducted the same as for a new piece, — the 
same time and degree of heat being required. The 
renewed heat employed renders the surface of the mate- 
rial previously vulcanized somewhat darker. It is claimed 
that this may be bleached by immersing the case in alco- 
hol and exposing it to the sun's rays for four or five 
hours. 

Bepairing without Pressure. 

The plate should first be cleansed ; then slightly oiled 
on the inside, and a cast run in it. When this has har- 
dened sufficiently, separate the plate and cast, also re- 
moving the broken teeth. Dovetails are now cut in the 
vulcanite plate, which is then replaced upon the cast and 
the teeth ground into position; after which they are 
removed, and the surface covered by them is painted with 
liquid rubber, as are also the teeth and pins. The teeth 
are then replaced, and heated rubber packed solidly 
under them and into the dovetails. The whole is then 
invested in one mass of plaster and vulcanized in the usual 
way. This does away with the flaskings, and shortens 
the time materially. 



FOR DENTAL PURPOSES. 45 

To repair where there is a crack through the plate, 
first fasten the parts together accurately with wax, and 
run a cast as previously described. The plate is removed 
from the cast, and a strip cut out the whole length of the 
crack. Dovetails are formed on either side. The pieces 
are then replaced upon the cast. If desirable, fasten 
them by investing in the lower half of the flask, leaving 
all places clear where the rubber is to go. The parts are 
then painted with liquid rubber, and the vulcanite packed 
solid. Finish flasking and vulcanize. 

Lower Plates with Suction. 

In 1866 Dr. George H. Hurd obtained a patent for 
what he termed the "Flange Suction" for lower plates. 
I have seen one of these plates in the mouth that has 
been worn for several years. It has a tenacious suction. 
The patient speaks of it in the highest terms, and says 
that from the first she has " experienced no trouble in 
wearing or keeping it in place." Dr. Hurd's directions 
for making these plates are in substance as follows : 

The impression is first taken in wax ; then, using that 
as an impression cup, with plaster of Paris. Cut off" the 
extreme projecting plaster down at the sides of the tongue ; 
varnish and fill up, making a full cast across from heel 
to heel, extending far back upon the process, to keep the 
lip from shoving the plate back when the muscles and lip 
are strained down upon it. 

Dr. Hurd uses gutta-percha base plate, first dipping it 
in hot water and the cast in cold water ; presses it down 



46 VULCANITE AND CELLULOID 

to the cast while hot. The antagonizing wax is allowed 
to strike first at the sides to keep the plate up against the 
gums. When the articulation is made the patient is 
instructed to swallow, to obtain a correct position. The 
teeth should be set directly upon the center of the mar- 
gin, perpendicular in front, and inclined a little at the 
sides, so as to give sufficient room to form a good outside 
flange for the lip to hold down upon; then throw around 
the outside three or four strips of sheet wax, making the 
flange one-third of an inch thick. The inside is rounded 
up inward similarly, only that it is not so thick and high, 
forming a flange for the tongue to rest upon and hold it 
down, and excluding the air. The saliva also settles under 
the tongue and assists in keeping out the air. The 
muscles of the lower lip fall in upon the outer flange 
and hold the plate down at will, keeping the air out of the 
chamber. The flange must rest gently against the cheek, 
to keep the plate steady and firm. The teeth must be 
kept level on the face, so that, if a ruler is laid down 
upon them, they will touch at once. Vulcanize by heat- 
ing slowly to avoid porous rubber. Finish by filing off, 
commencing at the hard margin on the under side of the 
outside flange, increasing it as you near the edge of the 
plate at the cheek, and forming a chamber ; also cutting 
away on the inside very much of the plate, as the sub- 
lingual muscles and glands under the plate will cause it 
to raise when the tongue raises. This flange can be made 
of flexible rubber and quite thin, without a cell, so as to 
hold firm and move with the muscles. But hard rubber 
will reach all cases and is more desirable. Dr. Hurd does 



FOR DENTAL PURPOSES. 47 

not recommend the flexible rubber unless in extreme 
cases of malformation. 

refitting grold or vulcanite plates with vulcanite 

Lining. 

A gold or vulcanite plate, which can no longer be worn 
in consequence of the absorption of the alveolar ridge, 
may be made to fit perfectly by using either of the 
following methods, as given by Dr. Richardson. The 
second method is preferred, as its results are more cer- 
tain : 

" First Method. — Take, for example, a full upper set on 
either gold or vulcanite. Secure, in the first place, an 
accurate impression of the mouth in its changed condition 
in plaster, and from this a plaster model in the manner 
usually practiced. Perforate the palatal portion of the 
plate with from eight to twelve holes at different points, 
and also the extreme borders, from heel to heel of the 
plate, at intervals of one-eighth to half an inch apart, and 
near the edges. These holes may be enlarged to the 
dimensions of a medium-sized knitting-needle ; or, if the 
piece is of vulcanite, to twice or three times that size. 

On the lingual and buccal surfaces the holes are well 
countersunk with a bur drill. The plaster model, with 
the central portion raised to form a chamber (and which 
should be made to correspond, as nearly as possible, 
in position, form, and thickness with the chamber in 
the plate, if one exists), is next heated throughout by 
placing it over a spirit-flame, or in the baking furnace 
of an ordinary cooking stove, or the muffle of a furnace. 



48 VULCANITE AND CELLULOID 

When of a temperature that will barely admit of its being 
taken in the hand, remove and cover the face of it with a 
sheet of India-rubber or gutta-percha, as prepared for vul- 
canite work, and press it down upon the face of the model 
with the fingers. Apply the perforated plate to the model, 
being careful to secure a proper relation of the two ; then 
press the former firmly down upon the model. To render 
the vulcanite material still more plastic and compressible, 
the whole may now be returned to the furnace and sub- 
jected to a uniform heat throughout, when it may be re- 
moved, and firm and steady pressure made upon the plate 
and teeth, until forced as nearly as practicable into con- 
tact with the face of the model. Portions of the gum 
will be forced through the apertures and out at the borders 
of the plate ; these should be well packed into the coun- 
tersinks and under the edges of the plate, when the model 
with the rubber plate adherent may be placed in a vul- 
canizing flask and incased bodily in plaster. It is then 
placed in the heater and vulcanized. If all the steps in 
tha process have been carefully conducted, the fit of the 
plate will be perfectly restored, with no material change 
in the antagonism, or none at least that is not susceptible 
of ready correction. The union between the vulcanite 
lining and the plate will be strong and lasting, and al- 
together impermeable to the fluids of the mouth. 

" In the case of lower pieces the holes should be made 
along the external and internal borders of the plate near 
the margins. In all other respects the manipulations are 
the same as those described above. 

" It is scarcely necessary to observe that, in the use of 



FOR DENTAL PURPOSES. 49 

gold plates, the method is inapplicable whenever it is 
designed to re-swage the same plate for the permanent 
piece. 

"Second Method. — Perforate the plate, whether gold or 
vulcanite, as before directed ; and, employing this as a cup 
or holder, take an impression of the mouth in plaster, 
pressing the plate up closely to the parts. The plaster 
forced through the holes, and filling the countersinks on 
the opposite side of the plate, will serve to bind the plas- 
ter to the plate, and prevent, with cautious manipulation, 
the two from separating as they are detached from the 
mouth. When removed, the plaster impression lining 
the plate is trimmed even with the borders of the latter, 
and varnished and oiled. The lower section of the vul- 
canizing flask is now filled with a batter of plaster on a 
level with its upper surface, and the impression, filled with 
the same, is turned over and placed in the center of the 
flask, with the edges of the plate touching the surface of the 
plaster. The plate and adhering plaster are now carefully 
separated from the model. After cutting out the plaster 
from the holes and countersinks in the plate, the plaster 
forming the impression is detached from the plate, and 
the holes and countersinks filled with wax. The plate is 
then readjusted over the model, and (the surrounding sur- 
face of the plaster in the flask having been varnished and 
oiled) plaster is poured in upon the upper surface of the 
plate and teeth, filling the upper ring. When the plaster 
is sufficiently hard, the two sections of the flask are sepa- 
rated, and grooves formed running out from the matrix 
to the margins of the flask. A sufficient quantity of vul- 



50 VULCANITE AND CELLULOID 

canizable rubber is now either placed upon the model or 
packed in upon the palatal surface of the plate; before 
doing which, however, the wax filling the holes and coun- 
tersinks in the plate (and which was placed there to pre- 
vent portions of plaster last poured, in forming the ma- 
trix, from running in and filling them up) should be 
worked out with a small instrument. The whole being 
sufficiently heated, the two sections of the flask are forced 
together, expelling redundant material. The piece is then 
vulcanized as in the former case." 

To Make a New Vulcanite Plate and Preserve the 

Articulation. 

Where from any cause an accident has happened to a 
plate which necessitates a new one, reproducing the exact 
arrangement and articulation of the teeth, the following 
method, as described by Prof. Wildman, may be employed 
with success : 

"Roughen the palatal surface of the rubber-plate, to 
cause the plaster to adhere to it ; then use it as an impres- 
sion-cup to take a plaster impression, being careful when 
it is in the mouth to preserve the articulation. In this 
impression cast the model ; trim, and cut keys or conical 
holes at several points in its outer face. Now, before 
separating the impression from the model, make a cast 
of the face of the teeth in two or three perpendicular 
sections extending to the base of the model, using 
a solution of soap or other t , parting substance on the 
plaster mold. Remove this mold of the face of the 



FOR DENTAL PURPOSES. 51 

teeth, which indicates t their true position relative to the 
model. Then take the impression from the model. By 
the aid of heat sufficient to soften the rubber, remove the 
teeth from it. Next make a model plate with prepared 
gutta-percha," wax, or modelling compound. " Now secure 
the sections of the mold of the face of the teeth to the 
model (their place will be indicated by the keys) ; adjust 
the teeth in their proper positions in the plaster mold of 
them, and build up with gutta-percha or wax to the proper 
form of the model set. This being done, test its accuracy 
of contour and articulation by placing it in the mouth. 
Then, using the model, proceed as for making a new set." 

As will be seen by the preceding, it is necessary that 
the patient be present, — first for the impression ; then for 
the placing in of the trial plate ; and, finally, for the fit- 
ting in of the case. This would all be required if the orig- 
inal plate was not accurate in fit and articulation ; but 
when it is, and this process is rendered necessary by 
breakage, the author has adopted the following method, 
in which the presence of the patient is not required : If 
the plate is broken into two or more pieces, it may be fast- 
ened together by holding the parts in position and drop- 
ping hot wax upon them. This being done, oil the palatal 
surface of the original plate, and cast the model in it; 
trim to the edges of the plate, giving the usual form to 
the model, making conical holes to secure the sectional 
molds of the outer face of the teeth as described in the 
previous method. When hard, remove these plaster sec- 
tions, and also the plate, from the model. 

To avoid fracture, the plaster cast and rubber plate may 



52 VULCANITE AND CELLULOID 

be heated until the vulcanite readily yields, when they are 
easily separated without injury. After removing the 
plate, proceed the same as described in the previous 
method, except that the case is packed and vulcanized 
without trying it in the mouth. 

When the plate is cracked in half, after waxing the 
broken parts together, secure a model as directed. The 
outer guides will not be required. Remove the denture, 
and with a fine Swiss saw cut away the palatal portion of the 
plate to within about an eighth of an inch of the inner sur- 
face of the teeth. In this remaining portion cut dovetails 
to retain the new rubber, and also form an undercut chan- 
nel in the portion which fits over the alveolar ridge in the 
line of the break as far as the edge of the rim ; secure the 
parts to the model with wax. The cut-out palatal portion 
may then be laid back in place, to aid in waxing up that 
part. Invest in the flask covering the labial and grinding 
portions of the teeth as in other repair work. After sepa- 
rating, remove the part desired to be replaced with new 
material ; pack and vulcanize as usual. 

Bleaching Vulcanite. 

To bring out the color of vulcanite, it should be 
bleached. This is particularly the case with pink rub- 
bers, as their appearance is unsightly without it. After 
the denture is finished and ready for the mouth, place it 
in a glass vessel, covering it with alcohol, and expose it 
to the rays of the sun from one to six hours. The vessel 
should be covered with glass to prevent the alcohol from 
evaporating. 



FOR DENTAL PURPOSES. 53 

Air-Chambers. 

Where air-chambers are required, and they are not cut 
in the impression, block-tin or sheet-lead covered with tin 
(which may be obtained at the dental depots) may be used. 
They should be about No. 16 (United States gauge) in 
thickness. The shape should be in miniature of the 
arch, and they should be placed as nearly as practicable 
in the center of the plate, which brings them posterior to 
the anterior palatine arteries and nerves. In many cases 
the Land air-chamber will be found preferable. 

To Construct a Vulcanite Plate without the usual 
Scraping and Polishing. 

This is done by waxing the case just as it is desired to 
have it when finished ready for the mouth. Burnish tin- 
foil over the wax (as described under the manipulations 
for " New-Mode " celluloid work) ; varnish the cast with 
shellac and press tin-foil evenly upon it, or (which is bet- 
ter) use a metal cast, and proceed in the usual manner. 
Instead, however, of picking the wax out upon separating, 
pour boiling water upon it. This leaves the tin upon the 
plaster. Pack the case and vulcanize. If care has been 
exercised, the case will be nearly finished, with the excep- 
tion of removing and polishing where the surplus has been. 

Mouths Having Soft Places. 

Dr. C. H. Land described the method of managing these 
cases, in the Dental Cosmos, vol. xxv., page 557, as fol- 
lows : 



54 VULCANITE AND CELLULOID 

" To secure good results in an artificial denture, a cor- 
rect impression is first in order and first in importance. 
Plaster of Paris is, in our estimation, the only material 
with which a normal impression can he ohtained. The 
various other materials used for the purpose force the 
muscles and soft tissues out of position, resulting in an 
inaccurate cast. Having secured a normal impression, — 
the negative from which a positive is to he obtained, — it 
should be considered as representing merely the outlines ; 
the conditions to be noted after a careful study of the 
parts. With the patient in the chair and the cast in hand, 
the conditions may be indicated by a series of characters 
and figures penciled on the cast. For instance, the thick- 
ness of the tissues may be represented by figures 64, 32, 
16, 8 ; the sixty-fourth, the thirty-second, the sixteenth, 
and the eighth of an inch in thickness, i^will indicate 
flexible ; H, ridged, etc. With such a record an intelli- 
gent idea can be formed of the requirements in the par- 
ticular case, and the necessary modifications will be easily 
comprehended and accomplished; the adaptation to the 
hard and soft, rigid and flexible, parts secured ; the press- 
ure obtained just where wanted — most in the soft parts, 
and least in the rigid. In order to trim a cast judiciously, 
one must have a thorough understanding of the individual 
mouth. A very important consideration is to so conform 
the plate to atmospheric pressure principles that in its use 
the soft parts of the mouth will be molded by the denture. 
The movements of the tongue and the direct pressure of 
the lower jaw contribute largely to bring about this result. 
The fact that the mouth does thus conform to the denture 



FOR DENTAL PURPOSES. 55 

shows the importance of a careful preparation of the cast, 
in order that pressure may be brought to bear where it is 
most efficient and least distressing, and to secure atmos- 
pheric pressure in establishing adaptation and retaining 
the plate. 

" The surface of the plate should always be finely fin- 
ished ; a rough and uneven surface prevents nice adapta- 
tion, and is unclean and unhealthy. With air or any for- 
eign substance between the denture and the surface of the 
mouth covered by it, perfect contact is prevented. If both 
rubber and celluloid plates were more highly finished be- 
fore insertion in the mouth, there would be less complaint 
of these vegetable bases for artificial dentures. 

. "At the level of the sea the atmospheric pressure is 
said to be fifteen pounds to the square inch, but no such 
amount of pressure is required to retain a properly fitting 
artificial denture. The saliva or fluids of the mouth are 
also of great importance in retaining a denture in position. 
If the plate and mouth were made perfectly dry, it would 
not be easy to secure such adaptations as would be re- 
quired to hold the plate in position. The utility of the 
atmosphere is not, however, fully demonstrated in the re- 
tention of a plate until an air-space is created by means of 
an air-chamber. This air-chamber should cover at least 
four-fifths of the palatine arch, and include certain parts 
of the alveolar walls. With this provision and a judicious 
trimming of the plaster cast on the outer portion of the 
alveolar ridge, a large part of the denture is made to act 
as an air-chamber, and this should be understood as but a 
temporary means in assisting the mouth to conform more 



56 



VULCANITE AND CELLULOID 



readily to the denture ; the result will he vacuum hy com- 
plete contact, which does not take place until all the air is 
excluded, and the air-space filled up hy the mouth con- 
forming to it. 

" To insure a comfortable adaptation, the pressure must 
he so equalized that, as the alveolar ridge recedes, undue 
stress will not be brought on the hard palate. For this 

Fia. 13. 




reason an air-space, covering almost the entire surface of 
the palatine arch, is desirable, as thus the pressure is bet- 
ter distributed and brought to bear directly on the alveo- 
lar ridge, where there will be the least danger of injuring 
the mouth, and thus avoiding the riding or rocking of the 
plate on the hard palate. The conventional air-chamber, 
with its acute angles invariably placed on the most rigid 



FOR DENTAL PURPOSES. 57 

portion of the hard palate, soon outlines itself in the tissues, 
demonstrating a failure to properly utilize atmospheric 
pressure, and injuring the mouth by inducing absorption 
unnecessarily. 

" The illustration (Fig. 13) is an exact copy of a mouth 
for which I am now preparing a set of continuous-gum 
teeth. The conditions may be indicated by letters, A, A, 
A, 64, 4, meaning that within these outlines the tissue is 
about the sixty-fourth part of an inch in thickness at one 
end and one-fourth of an inch at the other ; H, H, H, very 
rigid ; C, (7, (7, 16, the one-sixteenth of an inch in thick- 
ness; B, .B, B, very sensitive to pressure; 32, 16, 32, 
mean parts of an inch in thickness. On the side, A, A, A, 
a large piece of the process had been torn away in ex- 
tracting the first molar, which accounts for its peculiar 
condition." 

To Remove Teeth from a Vulcanite Base. 

The teeth must first be passed through a flame until 
hot, or immersed in oil and boiled. The author prefers 
covering the denture with sand and heating for a few 
minutes, when the teeth are easily removed by inserting 
a pointed instrument between them and the plate, leaving 
them clean and without the disagreeable odor of the rubber 
(unless they are made too hot) or breaking of the blocks. 

Repairing Vulcanite with Amalgam. 

It is sometimes necessary to make a quick repair of a 
case where there is one tooth or a block broken. This 
may often be done by forming a globular-shaped under- 



58 VULCANITE AND CELLULOID 

cut in the plate, and grinding the hlock into place and 
holding it there while packing in strong, quick-setting 
amalgam. I have done this on several occasions, and 
find that it works very well. 

Repairing Vulcanite with Shellac. 

Where there is a small hole in the plate, it may be 
repaired so that it will last for some time, by mixing 
gum shellac and vulcanite filings. This is heated and 
dropped into the hole; then made smooth with a hot 
spatula. 

To Repair Vulcanite Plates with Wood's Fusible 

Metal. 

For resetting a tooth or block, enlarge the socket 
within, cutting a dovetail in the plate for anchorage. 
Mold the metal into the socket with a hot spatula. 
Heat the tooth so that it will melt the metal, and press it 
into place. With the thumb, covered with cloth or 
chamois, mold the metal into shape. When it is con- 
gealed it may be built up where needed. In other cases 
the tooth may be retained in its place with the finger, or 
by means of plaster, as for soldering, and then cemented 
to the metal. Pins without heads should be bent, so as 
to retain their hold, always molding the metal securely 
around them. When there are holes in the plate to be 
sealed up, they should be countersunk on both sides, and 
the holes, if round, made oblong or angular. 

Liquid Rubber. 
To make rubber liquid any of the following solvents 



FOR DENTAL PURPOSES. 59 

may be used : Benzine, turpentine, ether, chloroform, 
and bisulphide of carbon. The rubber is cut into small 
pieces, placed in a vessel, and covered with either of the 
above liquids. 

Spring Plates. 

These are available only in partial cases, and are very 
little used, as their general tendency is to force the teeth 
out, particularly where the plate presses too hard against 
them. Scrape just a little away from the palatal portion 
of the bicuspids and molars upon the cast; grind the 
teeth into place, and wax them up, allowing the wax to 
extend about half an inch from the teeth all around, and 
leaving the central portion of the mouth uncovered. 
Air-chambers or clasps are not used in connection with 
this work. 

Articulating the Teeth against Vulcanite. 

The following is given by Prof. Wildman, and is often 
of great advantage : "In upper sets, when there are only 
a few under front teeth remaining, and they are irregular 
as to position or height, it is advantageous to form an 
articulation with rubber just back of the points of the 
artificial teeth. This is done, after the teeth are arranged 
upon the model plate, by placing soft wax upon the back 
of the teeth, and allowing the patient to bring the jaws 
together sufficiently to form the desired articulation. 
An impression of the antagonizing surfaces of the under 
teeth is thereby secured, which must be carefully pre- 
served in the model, and also in finishing the rubber set. 



60 VULCANITE AND CELLULOID 

This will in many cases prove of great utility, giving a 
bearing for the natural teeth, which could not be obtained 
otherwise without making the artificial teeth irregular 
and unsightly. Again, there are many cases, when the 
front teeth are properly articulated, in which we find 
some one or more of the inferior molars projecting up so 
far as not to admit of the use of an antagonizing porce- 
lain tooth having sufficient substance to enable it to bear 
the force of mastication. In such cases rubber may be 
substituted with good results. The proper length and 
form of the antagonizing face may be obtained with wax, 
on the same principle as mentioned in the preceding 
case." 

To Take the Warp out of a Vulcanite Plate. 

It is claimed that the following manipulations will take 
the warp out of a vulcanite plate, when from any cause 
it has sprung. Obtain a correct impression of the mouth, 
and run a plaster cast in it. Heat the vulcanite plate in 
an oven, teeth downwards. Allow it to remain a few 
minutes until the plate becomes pliable, being careful not 
to blister it by overheating. It is then placed upon the 
cast and forced into position at all parts; pressed down 
with a napkin and held until cold. It may be changed 
by heating in boiling water, and proceeding in the same 
manner. 

Solution of Soap foe Separating Plaster. 
Some prefer the employment of soap to shellac varnish 



FOR DENTAL PURPOSES. 61 

in separating plaster, and for the benefit of such the 
following formula is given : 

R • — "White soap, J i ; 
Eain water, O i. 

The soap should be cut into thin strips, and put in the 
water, which is heated to the boiling point, dissolving the 
soap. It is then bottled for use. In employing this solu- 
tion, pour out what is needed for the occasion, throwing 
away what is left. Do not put the brush in the bottle 
after using it upon the plaster, as it causes the solution to 
become turbid. 

Coloring Plaster for Impressions. 

Where the soap solution is used, it is better to color 
the impression, so that the line between it and the model 
may be readily seen when separating. To color the 
plaster, a little aniline may be placed in the water, in 
which it is mixed, or a little vermilion added to the dry 
plaster will answer the same purpose. This does not 
injure the material. When shellac varnish is used, it is 
unnecessary to color the impression, as the varnish im- 
parts color enough to be easily detected upon separating. 

Packing for Vulcanizers. 

Packing made with a web is the best, as that without 
softens too much upon being heated. When a new 
packing is required, remove all of the old and press the 
new into its place by means of a chisel-shaped instru- 



62 VULCANITE AND CELLULOID 

ment. An old penknife will answer the purpose. Before 
screwing the top upon the vulcanizer, dust either pow- 
dered soapstone, whiting, or stove-blacking upon the 
new packing. This will prevent its adhering to the 
vulcanizer or tearing upon opening. 

Porcelain Teeth Attached to a Metal Base with 
Rubber or Celluloid. 

The following method of attaching porcelain teeth to a 
metallic base is far superior to that of soldering, for 
several reasons : The contour may be restored the same 
as when a vulcanite base is used. This process is more 
cleanly, because the permeation of the secretions of the 
mouth will not take place, as in soldered cases. There is 
no danger of warping the plate from soldering the teeth to 
it, and the liability of fracturing the teeth is less, as they 
rest evenly upon a solid base. An injury to them is easily 
repaired without changing the plate. Gold, platinum, or 
silver may be used for the base. "When silver is used, it 
must be tinned where it comes in contact with the vul- 
canite, as the sulphur in the rubber destroys the silver. 

Dr. P. GL C. Hunt employed this method as early as 
1859, and published a description of it. It is practically the 
same as that for which Dr. S. D. Engle obtained a patent 
some years later. The manipulative details, as described 
by Dr. Hunt, are here given : 

" Take the impression, make metallic dies, and form 
the plate as for work in the ordinary way. After fitting 
the plate in the mouth, get the articulation, the fullness, 



FOR DENTAL PURPOSES. 63 

and length of the teeth ; remove the wax and plate from 
the mouth, and make the plaster articulation. If a full 
set, after separating the articulation, and before removing 
the wax from the plate, take a small, light pair of dividers, 
set them say an inch apart, and with one point following 
the margin of the wax representing the cutting-edge of 
the teeth, and the other point marking permanently the 
plaster, you have always in the dividers so set a gauge for 
the length of any particular tooth. A convenient substi- 
tute for the dividers may be formed from a piece of wire 
of convenient length, one-half the diameter of a common 
excavator, by suitably twisting its middle for a handle, 
and its ends being sharpened and pointing in the same 
direction, one or one and a half inches apart. 

" Thus far we proceed as we do for ordinary gold plate 
work. We will now suppose the teeth ground and 
jointed, leaving as much space between the teeth and 
plate as the plate will admit of. We next mark with a 
sharp-pointed instrument on the labial surface of the 
plate each point where it is necessary to place a loop for 
purposes hereinafter described; then apply wax to the 
external or labial parts of the teeth and plate in any 
manner sufficient to retain the teeth in position ; remove 
the wax from the lingual parts of the teeth and plate, 
and mark the position on the metal where it is desirable 
to insert the loops ; remove the teeth and wax, and with a 
small bow-drill make holes through the plate at the several 
points previously determined on for the attachments, 
about the size of the ordinary plate punch-hole; take a 
wire or ordinary gold plate cut in strips say from a half 



64 



VULCANITE AND CELLUOLID 



to one line in width, being governed by the amount of 
room there is under the base of the teeth, and with small, 
round-nosed pliers bend the strip around; grasp both 
ends with square-nosed pliers; draw the round-nosed 
pliers from the loop, still grasping the square-nosed pliers 
with the left hand, and with a hammer strike the top of 
the loop a sufficient blow to keep the ends from springing 
apart ; cut off the ends, and dress down to fit the holes in 
the plate; after which solder on charcoal or other suit- 
able substance without investment. [Fig. 14 illustrates 
the bent or hooked wires soldered to the base.] 

Fig. 14. 




" Pickle, dress, and polish that portion of the plate to 
be exposed to view. Bend and flatten the pins ; arrange 
the teeth according to the articulation, waxing so as to 
cover up the loops, if practicable. The loops should be 
placed as near the base of the teeth as possible, the 
rubber forming, when finished, a part of the general con- 
cave shape which is desirable in upper dentures, and 



FOR DENTAL PURPOSES. 65 

which it is not possible to obtain with ordinary soldered 
work. Then with silicate of soda paint the joints, to 
keep the rubber from forcing in where it would show 
after vulcanizing. Flask, vulcanize, and finish as usual." 

The rubber may be allowed to project beyond the edge 
of the plate on the labial surface, if desirable, and this in 
many cases will be found to be very satisfactory, as by 
such means the rubber may be left thick near the alae 
of the nose, when the loss of the cuspids may necessitate 
a support to the soft parts adjacent, and which in this 
manner can be readily supplied. If the rubber extends 
upward so far as to irritate the parts, a few minutes will 
suffice to make the necessary alteration. 

When celluloid is used for attaching the teeth, the pala- 
tal portion of the blank should be sawed out, leaving 
only the part covering the alveolar ridge, which may be 
trimmed away so that there will be but little excess of 
material. For lower plates the ordinary full lower blank 
is used, trimming to suit the case. After preparing the 
blank in this manner, the manipulations are the same as 
for a celluloid base. The teeth being arranged upon the 
metal plate and the contour restored in wax as desired, 
fill the plate with plaster, and also the lower section of the 
flask. Imbed the plate in this, forming the line of sepa- 
ration at the edge of the wax rim, thus allowing the pala- 
tal portion of the metal to be covered with plaster. After 
the other section is formed, separate as for vulcanite. 
The metallic plate will remain in the lower section, and 
the teeth in the upper. With celluloid, plain teeth are 
preferable. 



66 VULCANITE AND CELLULOID 

To attach either vulcanite or celluloid to a metal plate 
where the teeth are not soldered, the writer submits the 
following directions : Either turn a band upon the outside 
of the plate, and solder wire, marking the border of the 
wax upon the palatal surface, or solder wire around the 
labial portion, turning at the heel, and bringing it upon 
the palatal portion of the plate, forming a border for the 
rubber or celluloid that supports the teeth. Small loops 
or headed pins must be soldered on the plate for the ma- 
terial to grasp. In this way the necessity is obviated of 
drilling holes in the plate. After the wire and loops are 
soldered, the plate may be re-swaged, if it has sprung. 
The counter-die should clear the wire on the outside, or it 
will be forced off. The pins or loops may be raised after 
the re-swaging. It is not absolutely necessary to use the 
wire or turned band. 



FOR DENTAL PURPOSES. 67 



CELLULOID. 



Celluloid was brought into use about the year 1869. 
Since then it has been employed as a base for artificial 
dentures to a considerable extent. At the present time 
there are three modes of molding it, — namely, with steam, 
glycerin or oil, and by dry heat. The last mentioned 
seems to give the best results. Either plain or block teeth 
are used. The manipulations are similar to those for vul- 
canite, until flasking. 

Flasking for Celluloid. 

The mixed plaster should be free from air-bubbles. In 
all cases part the flask at the edge of the wax. When 
there is considerable undercut at the anterior part of the 
alveolar ridge, cut off the heel of the cast before flasking. 
This elevates the anterior portion so that pressure is 
brought to bear in a direct line upon the part that is 
undercut, thus avoiding the danger of fracturing. (See 
Fig. 25). It is sometimes necessary to cut away the thin 
edge of plaster which projects over the matrix, in the half 
of the flask containing the teeth. Place the two sections 
of the flask together, and see that there is enough room 
at the anterior part of the cast, as, if this precaution is not 
taken, the cast may be broken or pieces of plaster mixed 



68 VULCANITE AND CELLULOID 

with the celluloid. After separating, remove the wax 
thoroughly with boiling water. Powdered soap-stone, 
rubbed over the cast, prevents the plaster from adhering 
to the plate. Cut a groove for the surplus around the inside 
of the flask, not less than one-eighth of an inch from the 
cast, and entirely in the half containing the cast. There 
should be no cross-gates connecting the groove with the 
model, and the groove should be large enough to receive 
all of the surplus, as it is very hard to bring the edges of 
the flask together where it will not hold the excess. 

It is well, especially with gum teeth, where there is 
much surplus, to trim the plaster all around between the 
cast and the edge of the flask to about the thirty-second 
of an inch. This will give the material a chance to es- 
cape. All the sharp edges of the plaster liable to fracture 
should be rounded off. In the case of gum teeth holes 
should be drilled opposite to each joint, not over one- 
eighth of an inch in diameter, and as deep as desired. 
This relieves the blocks from some of the pressure. 

Molding. 

A blank should be selected as near the size of the cast 
as possible, and should not be wider than is necessary, as 
folding in from the sides is liable to take place, forming 
creases in the plate. 

The author gives, with some modifications, the molding 
process of the steam and glycerin machines of the Cellu- 
loid Manufacturing Company. 

Fig. 15 is a sectional diagram of the celluloid steam 
machine. 



FOR DENTAL PURPOSES. 



69 



Molding in the Steam Apparatus.— Till the boiler partly 
fall of water. The amount is not material, but there 
should always be enough to cover the ribs at the bottom. 
Have the screw well turned back, until the plunger when 



Fig. 15. 




placed in position will rest against the top of the boiler; 
otherwise the flask may be pressed upon while screwing 
down the cover, and the cast injured. Turn down the 
cover snugly ; see that the gland is turned back, and the 



70 VULCANITE AND CELLULOID 

screw works freely. Many failures have occurred by 
neglecting this simple matter. If it works hard, it is 
impossible to tell how much or how little pressure is being 
exerted. There may be too much, and blocks or cast may be 
broken ; or too little, and the plate made porous. In all 
methods of working celluloid, the sense of feeling is the 
best guide as to when and how hard to turn ; but in order 
to have this there must be perfect freedom of motion of 
the parts. The time elapsing before turning is not reli- 
able, as it varies with the heat employed, the temperature 
at starting, the amount of water in the boiler, the drafts 
of air to which the flame may be subjected, etc. 

After placing the flask in position, turn down the screw 
very gently with thumb and finger, until you feel it touch 
the flask. Fill the cup with alcohol and light it, or light 
the gas. The safety-valve is made in two parts. The 
upper portion may be suspended by the pins in the 
lead weight; the valve will now blow off steam (if in 
proper order) at a temperature of 225° F. Until this 
occurs no particular attention is necessary, but from that 
time the exclusive attention of the operator should be 
given to the molding. Many failures occur from the 
want of this, for the plate may be easily injured from too 
much heat without proper pressure. But fifteen or twenty 
minutes, at the most, will be required from this point, 
with proper heat, and nothing else should be attended to. 

At the point when the steam escapes from the valve, 
with the upper portion suspended, the plate will soften, 
and the screw will be felt to yield to light pressure with 
thumb and finger. The upper weight should now be 



FOR DENTAL PURPOSES. 71 

dropped down. Turn the screw very carefully, stopping 
when you feel the resistance increase ; as soon as it yields 
again, turn it more, going slowly and carefully at first, 
but increasing the pressure somewhat as the steam in- 
creases, which you will know by occasionally raising the 
valve. It is just here that judgment is required, — to avoid, 
on the one hand, too much pressure before the material is 
sufficiently softened, which would result in fracture of the 
cast or blocks, disarranging the articulation, or a " flaky " 
plate ; and, on the other, too little pressure after the heat 
is up, which would result in injuring the quality of the 
material. The pressure should be followed up as the heat 
rises and the screw yields, the object being to get the 
whole of the plate under pressure, in every part of the 
mold, by the time the steam blows off quite sharply and 
steadily on raising the safety-valve. After this the pres- 
sure should be increased, but time should always be given 
between the turns for the slowly-flowing celluloid to 
escape from under the pressure. Toward the close of 
the process the pressure should be considerable ; in fact, 
about all that can be applied with the machine, and 
should be continued as long as the screw can be turned. 
If the operation has been properly timed, the steam will 
blow off at the safety-valve at about the time the molding 
is completed, and the alcohol in the cup is consumed. If 
it should blow off before that, no harm would be done, 
as the heat cannot become too great if the safety-valve is 
kept in proper condition. These remarks apply to the 
use of alcohol in the cup furnished with the machine. 
If any other heat is used, the flame should be sufficient 



72 



VULCANITE AND CELLULOID 



to complete the process within thirty to forty minutes. If 
more than this time is consumed in the molding, the 
quality of the plate is injured. 

Molding in Glycerin. — Follow the directions already 
given until the flask is ready to he placed in the tank. 
Having placed the blank in the flask, put it into the screw 
clamp and turn down the screw until it touches the flask 

Fig. 16. 




lightly; set the whole into the tank, and pour enough 
glycerin into the latter to come about up to the top of 
the flask. Two pounds of glycerin should be procured ; 
usually a pound and a half will be sufficient to cover the 
flask, and the remainder can be kept to replenish the 
tank. The glycerin is left in the tank when not in use, 
and does not evaporate, but there is a slight waste by 



FOR DENTAL PURPOSES. 73 

adhesion to the flask and clamp, which should be allowed 
to drain off into the tank, and the waste will be so slight 
that the amount named will last a long time. 

The heat having been applied, as soon as it is sufficient to 
cause the screw to yield to gentle pressure (about 225° F.), 
begin the molding, turning very lightly at first, as di- 
rected for the steam machine, and continuing as the 
material is felt to yield, increasing the pressure to a heavy 
one as the flask is closed. A great advantage of this 
process over the steam is that the flask can be lifted out, 
and the progress of the closing watched. If the flask 
closes unevenly, loosen up the screw, and sliift the flask 
so as to bring the pressure where required. The heat 
should not be permitted to rise much above 280° F. If the 
flask is not closed when that heat is reached, reduce the 
flame, and do not hasten the closing. A little practice 
will enable the operator to graduate the pressure exactly, 
without reference to the thermometer. Lard or oil 
may be used instead of glycerin, but they are not as 
cleanly. 

Fig. 16 represents the improved glycerin machine and 
screw-clamp. 

Cooling and Kemoving. 

After the screw is down, put out the flame, and at once 
reduce the temperature by blowing off steam. Allow the 
flask to become thoroughly cold in all cases before re- 
moving the plate. The cooling may be hastened without 
injury by setting into cold water, but the flask must be kept 
closed by a flask-clamp or otherwise until entirely cold. In 



74 VULCANITE AND CELLULOID 

cases where the material is of extra thickness, or where 
the shape of the blank is totally altered, longer seasoning 
is advisable, and the flask should be placed near a stove 
or over a register (keeping it closed with a clamp) for 
half a day or more, at a temperature not over 140° F. If 
these directions are observed, no trouble from warping 
plates will be experienced. 

Caution. — Do not use a longer handle than the one 
furnished with the machine. Do not allow the water to 
be all converted into steam, as the steam would then 
become superheated, and a dangerous condition ensue or 
the plate be ruined, while the safety-valve would not indi- 
cate it. Always have plenty of water in the boiler, and, 
if steam should cease to issue on raising the value, the 
heat should be at once withdrawn. 

Eepairing. 

Cut away the plate, and fit in the new teeth or block. 
Form dovetails. Always, if possible, before flasking, fit a 
new piece, much larger than the portion cut away, to the 
plate as closely as possible, allowing it to come close to 
the added teeth ; then, having the surfaces clean, cement 
it fast with spirits of camphor, or a solution of celluloid in 
camphor. (See " Liquid Celluloid.") Allow it to dry, after 
which the new teeth should be waxed into place. Invest 
the piece in the flask, covering the whole plate and teeth 
in the plaster, except the added piece, which should be 
left at the bottom of a well or depression in the plaster. 
Figs. 17 and 18 represent the manner of repairing. Fig. 



FOR DENTAL PURPOSES. 



75 



17 shows the first step in the process, the plate being 
cut away and the new piece (shown at a) fitted and 
cemented in place. After drying a short time (allowing 
it to stand a few hours or over night, if convenient), fit 
the new block to its place, leaving as little space as possi- 
ble between the plate and the block. This space is to be 
waxed up to keep out plaster when investing. Fig. 18 
shows the piece invested, the whole plate and teeth, ex- 

Fig. 18. 



Fig. 17. 





cept the new piece a, being covered deep in the plaster, 
which is trimmed as shown. The upper part of the flask 
is now put in place, and filled in the usual manner. On 
opening the flask, boil out the wax. Then lay another 
piece of celluloid, or a ball of tin-foil, or moistened 
blotting-pad — in fact, anything that will produce pressure 
— upon the piece a, and heat up and press as usual. 
In this way the new piece becomes a part of the plate by 
the cementing process, before the pressing is done. If 
neatly repaired, the line of junction will be scarcely ob- 



76 



VULCANITE AND CELLULOID 



servable. The sharp edge of the plaster at the bottom of 
the well or depression should be trimmed out and rounded, 
as otherwise these edges are liable to fracture and get into 
the plate. If the new block or tooth is separated from 
the plate, so that it has no support, and is liable to be 
pushed down, it should be supported by crowding a small 
bit of celluloid under it before beginning. The new 
piece may be placed in position after opening the flask, a 
few drops of spirits of camphor added, and the case 
pressed as before ; but union by this means is not nearly 
as certain. There is no certainty about uniting pieces in 
the machine. It may be done or it may not. But by 
cementing well-fitting or freshly-filed surfaces together 
outside the flask, union may be had, and pieces added 
wherever desired. 

Care should be taken to avoid air-bubbles in the plaster, 
and to pour it smoothly. 

If the plate is of sufficient thickness, the repair may be 
very nicely made without adding any new material. Fit 
the new block without cutting away more of the plate 
than is absolutely necessary. Invest the plate, leaving the 
lingual portion exposed, but covering the teeth ; on open- 
ing the flask, lay over the exposed plate one or more 
thicknesses of wet, thick brown paper, or blotting-pad, 
fitting closely to the teeth and having it thickest in 
the center, and press as usual. By this means the plate 
will be spread up to the new teeth, which will be firmly 
united. Loose teeth, if any, on the plate may be tight- 
ened by the same means, having been waxed in place, and 
the wax afterwards thoroughly boiled out. Some attempt 



FOR DENTAL PURPOSES. 77 

to repair plates in this way, without using anything to 
produce pressure, depending upon the swelling of the 
plate to fill the vacancy. This would be certain to injure 
the density of the material. 

To remove teeth, heat the plate in boiling water or 
glycerin, when they will come off easily. 

Rubber plates may be repaired with celluloid, but, as 
there is no union, dovetailing or drilling holes is neces- 
sary. 

Finishing. 

Use files, sand-paper, and scrapers, but do not use too 
coarse materials. Polish with pumice-stone, and finish 
with a soft brush- wheel, run at high speed, and whiting or 
prepared chalk. Dr. H. D. Knight, of Lancaster, Pa., 
recommends a polish obtained by rubbing with an old 
cloth wet with camphor. This is valuable between teeth, 
and in places inaccessible to the brush-wheel. In fin- 
ishing, care should be taken not to heat the plate by fric- 
tion, as by so doing the surface may be injured, or the 
plate sprung out of shape. 

Hints. 

If the teeth are not attached, or the celluloid is not 
closely and firmly molded around them, it is from one of 
two causes — either the principles mentioned under the 
head of " Porous Plates " have not been observed, or the 
plaster is poor. 

By wrapping the flask in muslin cloth, dirt is kept from 



78 VULCANITE AND CELLULOID 

entering it and mingling with the celluloid. When thin 
plates are used, care must be exercised in waxing up the 
case, so as not to have it too thick. 

Dark Lines. 

Where these appear on the palatal portion of the plate, 
it is the result of using a plate too wide for the mouth ; 
or of want of sufficient thickness in the center of the 
blank, causing the material to flow inward as well as out- 
ward, and fold upon itself; or, in deep mouths, from be- 
ginning the pressure too soon, which tears the plate 
asunder. 

Porous Plates. 

In the steam machine this cannot result from overheat- 
ing. The only other cause is want of proper pressure at 
the right time. The nature of celluloid is such that if it 

is subjected to a temperature of 270° F., without being 
under pressure, the camphor evaporates, and the material 
is puffed up, exactly as a loaf of bread is raised by yeast, 
and filled with air-cells. For this reason the overflow 
found in the waste-gates (if they are not full) will always 
be found porous, though it is no hotter than the rest of 
the plate. If the plate is porous, therefore, the pressure 
has not been brought down soon enough, and the plate is 
ruined in texture for want of it. This result may be 
partly reached, and the plate may not show it at first ; 
even after being injured it may be brought down by sub- 
sequent pressure to an apparently solid condition, but it 



FOR DENTAL PURPOSES. 79 

will never again be as dense or solid as it formerly was. 
The plate, however, may be porous in spots. This is the 
result of want of pressure, but it is caused either by a 
lack of a sufficient amount of material in a certain por- 
tion of the flask, or by too large cross waste-gates, or 
fracture of thin edges of the mold, either of which will 
relieve the material from the necessary pressure, and pro- 
duce porous spots in the plate. To secure the best results 
there should be not only enough but a slight excess of 
material in every portion of the flask. Celluloid cannot be 
depended on to flow from one portion of the flask to 
another, and there must always be enough directly before 
the cast to insure a plate of uniform density. 

Plaster. 

For the successful working of celluloid it is absolutely 
necessary to have the best quality of plaster. Very many 
of the difficulties experienced by dentists in working cellu- 
loid are due to the use of unsuitable plaster, as a very 
large proportion of that offered for sale is entirely unfit 
for the work. The fine and highly-calcined plaster has 
not the requisite strength, and will not stand the pressure ; 
blocks are broken, plates do not fit, the articulation is de- 
stroyed. For this use a good article of builder's plaster 
will be found far more satisfactory than the finer grades, 
although it will not set as quickly or be as white. Do not 
use salt, sulphate of potash, or other materials to cause 
rapid setting, as they lessen the strength. The use of 
tepid water will hasten the setting without injury. Put 



80 VULCANITE AND CELLULOID 

the plaster in the water (and not the water on the plaster),, 
allowing it to absorb all that it will take up, leaving no 
excess of water, making it as thick as can be well poured; 
stir it thoroughly and pour some into the flask or im- 
pression to be filled, and shake clown well. Then into 
what remains in the bowl stir more plaster, until you 
have a mass so thick that it can be piled up ; fill the flask 
with this and jar it down solidly. The thinner plaster 
first poured in will run and be driven, by the thicker after- 
wards added, into all the crevices, and most of it will es- 
cape from the flask, leaving a body of solid resisting 
plaster that cannot be obtained by the ordinary method 
of mixing. Of course, a very quick-setting plaster can- 
not be used in this way, but such plaster is not as 
strong as the slower-setting. The addition of a small 
portion 01 clean river-sand or marble-dust will be advan- 
tageous. 

Forming Plates before Molding. 

It is well to keep an assortment of all the blanks, so that 
one of proper form may always be at hand. Never use a 
plate much wider than the mold, as the material would be 
compelled to crush inwards. Nor should one be used 
which is not wide enough. A plate very dissimilar to the 
model always has more tendency to change its shape than 
one nearly adapted. By softening in boiling water, the 
plate may be pressed into any shape before molding, and 
an excess in any part may be trimmed off in the same 
manner with a sharp knife. 



FOR DENTAL PURPOSES. 81 

Metal Casts. 

Better results are obtained by molding either vulcanite 
or celluloid upon a metal cast than upon a plaster one. 
After a perfect cast is obtained in metal, there is no dan- 
ger of fracturing or brushing away small particles, as with 
plaster. The inner surface of the plate is finished with 
a hard polish, making it more agreeable even if the fit is 
no better. The cast is usually made of block tin, or some 
metal fusing at a low heat, and is manipulated as follows : 
Form the mold in sand (using the plaster cast as a pat- 
tern), and pour the metal into this. Where there is a 
heavy undercut, it would be impossible to remove the 
plate from the metal unless the cast is made hollow, which 
is done by pouring the metal into the sand mold, and al- 
lowing it to remain only long enough to cool upon the 
outside. Then turn it over, letting all of the molten 
metal run out; after which scrape away enough of the 
metal to leave only a thin shell. This forms the hollow 
cast. When cold, saw all around the alveolar ridge with 
a fine Swiss saw, leaving only enough connection to hold 
the parts in position. Pour the plaster into this, filling 
the saw-cuts and forming a solid cast. Now proceed as 
with a plaster model. When the case is finished and 
ready to remove, cut the plaster out of the inside of the 
die, and place the edges of the metal in a vise and crush 
it. This leaves the plate without injury. A metal cast 
may be formed by pouring it into the impression, pro- 
vided it is taken in plaster and the impression is thor- 
oughly dry. 



82 VULCANITE AND CELLULOID 

Have Enough Material. 

No one can expect that a plate will fit unless there is 
enough material to force the celluloid into every part of 
*the matrix. 

Cleanliness. — Keep the machines and flasks clean and 
free from plaster, and do not handle the plates with dirty 
fingers, especially when hot. Use clean water in the 
steam-hoiler. 

Care of Plates. — Patients should he instructed to keep 
their plates properly cleansed. Soap and powdered pumice 
are highly recommended for keeping celluloid plates clean 
and free from stain. 

Metallic Clasps and Backings. 

Where it is desired to use these, they may be nicely at- 
tached, hut the ends should be firmly anchored in the 
plaster, and the free ends should be supported by either 
pushing a small piece of celluloid under them, or bending 
at right angles and allowing the end to rest upon the plas- 
ter, which will prevent the displacement of the band or 
backing. (See Figs. 11 and 12. A drop or two of spirits of 
camphor may be placed on the parts, and the celluloid will 
tend to flow around them. 

Thickening of the Plate. — This, as well as displacement 
of the teeth and derangement of the articulation, is 
due to poor plaster, or to too hard pressure before the 
heat is up. 

Thermometers. — These vary sometimes 20° or 30°, and 
consequently machines used with them are unreliable 
until tests are made. 



FOR DENTAL PURPOSES. 



83 



The "Best" Hot Moist Air Celluloid Apparatus. 

Fig. 19 is a representation of the " Best " Hot Moist 
Air Celluloid Apparatus ; rigged for gas. 

This machine is spoken of in high terms by those who 
have used it. The case is flasked the same as for other 
machines. An essential point in the successful working 

Fig. 19. 




of celluloid by this method is to have the plaster in the flasks 
thoroughly wet. This may be attained by setting the flasks 
in a vessel of water before placing them in the heater. 

Directions for Using. — When the flask is prepared, with 
the plate in position, place it in the clamp and screw 
down the top until it slightly presses the flask. N"ow 
place it in the oven and apply the heat. 



84 VULCANITE AND CELLULOID 

The degree of heat may be determined with sufficient 
precision by moistening the end of the finger and apply- 
ing it to the flask, as the housewife tests the heat of the 
sad-iron. As soon as the contact of the moistened finger 
produces the peculiar fizz it is time to commence screw- 
ing the flask together. The condition of the plate may 
also be determined by probing with the point of a knife 
or of an instrument between the edges of the flask. By 
a sensitive touch the beginning of plasticity of the plate 
may also be recognized from a slight turn of the screws. 
As the material softens continue to put on more force 
(allowing a little time for the material to flow under the 
pressure), until the sections of the flask are brought 
firmly together, at which time the heat should be re- 
moved, so as to avoid overheating the plate and making 
it porous. 

An important point to be observed is, that while the 
flask must not be brought together until the heat has 
properly softened the plate, neither must it be allowed to 
remain open too long, as the plate will then become hard, 
from loss of camphor, and prevent the flask's being closed 
properly. Remove from the oven and allow it to cool 
gradually and thoroughly, the oven being meanwhile 
ready for another case. 

The foregoing directions have been prepared for the 
guidance of those who prefer to employ moist heat. The 
"Best" heater is also used by many of the most success- 
ful workers of celluloid as a dry heat apparatus, the fact 
that it may be used for either method constituting one of 
its most valuable features. 



FOR DENTAL PURPOSES, 



85 



THE NEW-MODE HEATER, CELLULOID MA- 
• CHIKE AND DENTAL VtTLCANIZER. 

This is the most desirable apparatus in the market for 
working celluloid, and any one, after becoming perfectly 

Fig. 20. 




Rigged for Gas. Can be adapted for Alcohol by 
substituting the lamp for the gas-burner. 

familiar with it, will give it preference for superior results. 
For vulcanizing it requires more time than other vulcan- 
izers, but it leaves the rubber stronger and of a better 
color. 



86 VULCANITE AND CELLULOID 

By permission, the author gives substantially the in- 
structions which are furnished with the New-Mode Heater. 
(Fig. 20.) 

The New-Mode Celluloid Machine and Dental Vulcan- 
izer and Packer combines in one apparatus important 
improvements in the means of working both celluloid and 
rubber. It is based on the conviction of the inventor that 
perfect work in either can only be made in a dry cham- 
ber, and that where a high degree of heat is used, such as 
is absolutely essential in the manipulation of celluloid, 
the temperature must be kept uniform until the work 
is completed, and must not be allowed to change sud- 
denly. 

Steam is used to heat up the packing-chamber and 
investment, but the chamber itself can be and for certain 
kinds of work must be kept absolutely dry after the mold- 
ing commences, while the complete control which the ope- 
rator has over the workings of the machine enables him 
to maintain the heat at any desired temperature. The 
hot-box or packing-chamber is nearly surrounded by the 
boiler, and steam may be admitted to or excluded from 
the packing-chamber at will. A case may be removed 
from the heater and another one inserted without reducing 
the temperature or letting off the steam from the boiler, 
thus accomplishing a large saving of time. The boiler 
has no steam-packed plunger or screw to cause uncer- 
tainty as to the amount of pressure applied. The top of 
the boiler is cast in one piece with the boiler ; the flask is 
closed with a small key-wrench by the thumb and finger, 
the screw-bolts for closing the flask passing through the 



FOR DENTAL PURPOSES. 87 

steam-chamber in piers or columns. A steam-tight plate- 
glass door permits the operator to examine the work at 
any time during the process of molding, enabling him to 
apply the proper pressure at the right time, thus reducing 
the liability to break the cast, investment, or teeth. 

The celluloid blanks used in dentistry are subjected to 
a process of " curing" before they are placed on the mar- 
ket. Dry heat has no injurious effect on the material. 
If a piece of transparent celluloid be passed through a jet 
of steam, the transparency will disappear in an instant, 
and the material will become opaque and lose its hard- 
ness. A piece of the same transparent celluloid, heated in 
a dry chamber to the same temperature as that of the jet 
of steam, is not affected, its transparency and hardness 
remaining unchanged. So, too, with rubber. A piece ot 
black rubber vulcanized by dry heat in the steam-tight 
packing-chamber of the E~ew-Mode machine is of a pure 
jet-black color when taken out ; while a piece of the same 
black rubber vulcanized by the ordinary method shows 
brownish discolorations. These simple experiments show 
conclusively that the action of the steam is the cause of 
the loss of quality. 

The cut (Fig. 21) is a sectional view of the working parts 
of the New-Mode machine, showing its construction at a 
glance. It is a cylindrical cast vessel, having two cham- 
bers, one within the other, the inner one being supported 
by piers or columns connecting its sides, top, and bottom 
with those of the outer chamber, the whole being made 
in one casting. The outer compartment is the steam- 
chamber, or boiler, and incloses the hot-air or packing- 



oo VULCANITE AND CELLULOID 

chamber on all sides except the front, where the walls of 
the two chambers converge and become one, for the pur- 
pose of permitting access to the packing-chamber. A door, 
made of the same metal as the boiler, and fitted with lead 
packing to make it steam-tight, is held in place by. a 

Fig. 21. 




bridge secured by screws. The door is also provided with 
a plate-glass light (shown in Fig. 20), through which the 
operator can watch the progress of the molding in 
the oven. The only communication between the two 
chambers is by means of a valve having its seat in the 
top of the packing-chamber, and controlled by a hollow 
stem which passes through the top of the machine. B is 



FOR DENTAL PURPOSES. 89 

• 

the mercury-bath; C, thermometer; D, screw-plug; E, 
lam-nut ; F, stem of steam-valve ; Gr, screw-cap ; H, large 
screw for closing the flask; I, I, I, smaller screws for same 
purpose ; K, K, K, L, nickel-plated caps for screws ; 0,0, 
steam chamber. 

Working Celluloid with the ISTew-Mode Heater. 

To secure the best practical results, celluloid should be 
molded or pressed into the form desired, at the highest 
possible temperature which will not burn it. To prove 
this it is only necessary to mold a plate on a metal cast at 
the lowest temperature at which it can be done, which is 
about 212° F., and another on the same cast at the high- 
est temperature possible, say 310° or 320° F., and lay the 
two aside for a few days, when it will be found that the 
one molded at the lower temperature will not fit the cast, 
while that molded at the higher temperature will fit as 
well as when first made. The reason is that the low tem- 
perature fails to overcome the tendency of the plate to re- 
turn to its original form, while the high temperature ren- 
ders it so thoroughly plastic that this tendency is entirely 
eradicated. This is proportionally the case with pieces 
made at intermediate temperatures ; the higher the tem- 
perature to which the plate is subjected in molding, the 
more exactly will it hold its new form and the less will be 
its tendency to warp. 

Celluloid may be readily and safely manipulated in the 
New-Mode Heater at 320° F., a temperature many degrees 
higher than is deemed safe in other machines, and which 



90 VULCANITE AND CELLULOID 

accomplishes perfectly the result above noted. When 
this very high temperature is employed the celluloid 
should be in the machine only long enough to permit the 
closing ot the flask; for the reason that heat vaporizes 
the camphor — the solvent of the material. If too much 
of this is driven off before the flask is closed, it will be 
almost impossible to mold the blank to the desired form. 
The sooner the flask is closed after being placed in the 
oven, the more readily will it be done and the better will 
be the result. 

The molded surface of a piece of celluloid is much 
more durable than its interior, and will retain the color 
better. It is obvious, therefore, that this surface is essen- 
tial to the integrity of the plate, and should be preserved 
intact. To insure this, the case should be so prepared 
that the plate, when taken from the flask, will require 
little or no labor to make it ready for use. It is possible 
that some surplus material at the edges may have to be 
trimmed off and the edges smoothed, but the case is not 
properly prepared if more than this is necessary. The 
care and trouble involved in proper preparation will really 
save time ; will absolutely avoid interference with the fit 
by the too free use of files, sand-paper, pumice, etc., and 
will insure as durable a plate as can be made in celluloid. 
Moreover, the artistic taste of the operator may be 
exercised before the plate is molded more readily than 
afterward. 

Directions for Preparing a Case for Celluloid. 
Use pink parafline and wax for base-plate. The inven- 



FOR DENTAL PURPOSES. 



91 



tor uses a thin paraffine-and-wax sheet as the plate, 
strengthened by pressing upon it a quantity of warmed 
paraffine or impression-compound, after first covering 
the paraffine plate with heavy tin-foil, so that the im- 
pression-compound can be removed and the smooth- 
ness of the original paraffine plate may be retained. 
Set the teeth on this in the position desired, and 
drop melted paraffine and wax around the roots. A very 
nice form of stick wax is made for this purpose. The 
method of dropping wax is shown in Fig. 22. After cool- 



F:g. 22 




ing, carve into the shape of gum desired. A simple 
scraper like that shown in Fig. 23 is excellent for carving 
the wax. 

Fig. 24 represents a very complete set of carving in- 
struments designed by Dr. W. W. Evans. ISTos. 1 and 2 
have steel points — at one end of each a carver similar to 
Dr. Kingsley's vulcanite finishers; at the other end a 
knife-blade, that of No. 1 being curved, while JS"o. 2 is 



92 VULCANITE AND CELLULOID 

straight. The points of No. 3 are ivory, having a wide 
range of usefulness as burnishers, and especially in work- 
ing the wax into the interstices to form the festoons of the 
gum. 

The wax may be made very smooth by throwing upon 
it the flame of a spirit-lamp, with the aid of a blowpipe 
or chip-syringe, taking care not to destroy the outlines of 
the carved gum. (It should be constantly borne in mind 
that one minute spent in careful waxing will save five in 
finishing.) Cover the wax with No. 60 tin-foil, burnish- 
ing it lightly but smoothly to the wax. 

Care must be exercised that no wrinkles are burnished 
in the foil, as they will show in the plate. The palatine 
portion must be of one piece, having no slits cut in it. 
The foil used on the outside of the gum takes the form of 
a horseshoe, and is burnished to the wax, allowing it to 
extend up a short distance on the labial and buccal sur- 
faces of the teeth. Turn the edges of the foil up one- 
fourth to one-half of an inch around the upper edge of the 
piece covering the gum; also the edge of the palatine 
piece. Invest in the shallow part of the flask with the 
wax and foil about one-eighth of an inch above the invest- 
ing plaster, cutting the usual groove for excess of mate- 
rial. Care should be taken that the wax, teeth, and foil 
are removed with the upper half of the flask in parting, 
leaving the cast clean and entirely exposed. 

Remove the wax by pouring boiling water over it from 
the spout of a tea-kettle or other vessel. The foil remains 
upon the plaster. The investment is now ready to be dried 
out preparatory to receiving the celluloid. 



FOR DENTAL PURPOSES. 



93 



IYg. 23. 



Fig. 24. 




94 VULCANITE AND CELLULOID 

Drying the Cast and Investment. 

There are two ways of drying the investment, — first, by 
raising the temperature to 320° ¥., keeping the hot-box 
dry; second, by admitting steam to the hot-box. The for- 
mer method can be used when the investment is placed in 
the chamber before getting up steam. If steam is up, 
however, either method may be employed. In using the 
dry-heat method, open very slightly the screw-cap of the 
piston or valve-stem to permit the escape of the steam 
generated from the water in the plaster, being careful 
that the steam-valve is firmly seated, as otherwise all the 
steam made in the boiler will escape. In using steam 
for drying, admit the live steam into the chamber 
with the investment by raising the valve from its seat, 
keeping the screw-cap closed. The steam quickly per- 
meates the plaster, and in five or ten minutes the temper- 
ature of the plaster is high enough to convert the water 
in it into steam. As soon as the plaster is thoroughly 
heated, shut off the steam by closing the valve, and raise 
the screw-cap very slightly to allow that in the chamber 
to escape slowly through the small aperture at the side of 
the screw. In a few minutes the cast will be perfectly 
dry, the steam escaping from the chamber carrying with 
it that generated from the moisture in the plaster. Ex- 
treme care should be taken that the steam shall escape 
very slowly, as otherwise the plaster may be blown out of 
the flask into the oven by the too rapid expansion of its 
vaporized moisture. The completion of the drying pro- 
cess is known by steam ceasing to be given off at the 



FOR DENTAL PURPOSES. 95 

screw-cap, Gr. The drying may be facilitated by placing 
a small chip of wood between the two parts of the flask 
when it is put into the chamber, thus exposing a larger 
surface to the heat and allowing the moisture to escape 
more readily. 

Molding with Dry Heat. 

When the investment is dried, remove it from the 
chamber and insert and carefully adjust the selected 
blank ; replace the flask in the oven immediately under 
the screws ; see that the two sections are so placed that 
the guide-pins will enter properly into the lugs ; open the 
screw-cap a turn or two to allow the escape of the gas 
from the hot-box ; turn down the large screw until it bears 
lightly upon the top of the flask, and close the machine. 
In less than iive minutes the material will be sufficiently 
softened to permit the commencement of the molding. 
The screws will turn readily with the thumb and finger 
(using the smaller key- wrench), when the blank is prop- 
erly softened. Close the flask gradually, stopping occa- 
sionally if the resistance is too great. Generally, if the 
temperature is about 300° F., the flask can be closed in 
ten minutes ; but if the blank is very thick, the molding 
must proceed slowly, the small screws may be used to 
advantage, and more time, say thirty minutes, may be 
consumed. As soon as the flask is closed — unless it is a 
locking-flask — the flame should be extinguished, the door 
opened, and the machine allowed to cool. If a lock-flask 
is used, it may be removed and thoroughly cooled before 
opening it, the oven being meanwhile ready for another 



96 VULCANITE AND CELLULOID 

case. The cooling may be accomplished rapidly, if neces- 
sary, by placing the flask in water. When perfectly cold, 
remove the plate from the investment ; it will be found 
enveloped in the tin-foil which had been burnished to the 
wax-plate. Peel off the foil. The celluloid will present 
a hard, brightly-polished surface, received from its contact 
with the foil, and will need no further finishing than cut- 
ting off the excess of material and smoothing down the 
edges. The extra hardness of the surface will thus remain 
to preserve the integrity and color of the piece. It is 
claimed, also, that the contact of the foil renders the outer 
surface, which is always the densest portion of celluloid, 
much harder. 

Imitating Gum Membrane. 

The plate produced by the above method is of the or- 
dinary appearance, with smooth, polished gum; but a 
much more natural, life-like gum will result if the tin-foil, 
after being burnished to the wax plate, is " stippled." 
Fig. 29. This is done by " dotting " carefully over its 
surface with a dull-pointed instrument, which should be 
held nearly perpendicular to the surface to be operated 
on. The strokes should be gentle — not hard enough to 
perforate the foil. When the foil is removed, after the 
case is molded, the gums present an appearance closely 
resembling the natural membrane. The stippling need 
not occupy a great deal of time, and the result it produces 
is a marked improvement. 



FOR DENTAL PURPOSES. 



97 



Fig. 25. 




Deep Undercuts. 

To obviate the difficulty of molding celluloid plates in 
cases of deep undercut, without breaking the plaster cast 
and producing a failure, the 
method described by the late 
Prof. Wildman, in the Dental 
Cosmos for March, 1875, is re- 
commended. This consists sim- 
ply in so investing the cast that 
it shall occupy the position 
shown in Fig. 25. If so placed, 
the pressure applied in molding is brought to bear upon 
the mass of plaster supporting the projection, instead of 
upon a thin section. 

Repairing. 

If a portion of a plate has been broken away and lost, 
fit a piece of celluloid of the proper shape, leaving it 
somewhat larger than the space to be filled. Make sure 
that the surfaces to be united are perfectly clean ; even the 
perspiration from the hand may cause a dark line. Flask 
and mold as usual. 

A crack in a plate or the parts of a broken plate may 
be joined by scraping the surfaces clean; forming dovetails 
in the plate each side of the crack ; moistening the edges 
with liquid celluloid or spirits of camphor, and molding 
a strip of celluloid into the seam. 



To Replace a Broken Tooth. 

Remove all portions of the broken tooth from the plate, 

7 



98 VULCANITE AND CELLULOID 

taking care not to disturb the outlines of the socket. Se- 
lect a tooth of proper size and shade to replace the broken 
one. (If the tooth is numbered, a considerable part of 
the trouble of selection may be saved by taking the num- 
ber of the mold from the reverse impression in the plate, 
or from the broken pieces.) 

To make the new tooth pass into the hole made by the 
old one, the hole must be made larger, and to do this the 
plate should be filled with plaster so that it will cover the 
front of the gums and face of the teeth, to prevent any 
possibility of warping the plate out of shape. Heat a large 
burnisher, or any suitable instrument, in boiling water ; 
place this in the hole several times until the celluloid has 
become warm enough to be pushed slightly towards the 
palatal portion of the mouth. This will enlarge the hole 
sufficiently to allow the new tooth to be inserted in its 
proper position. Pour plaster over the face of the tooth, 
to keep it from being forced out of place. Cover the 
bulge made in the celluloid, by stretching the hole to 
admit the tooth, with heavy tin-foil. Heat any suitable 
instrument in boiling water and press it against the bulge 
until the celluloid is forced firmly around the pins and 
tooth. The plaster in front prevents the tooth from being 
forced out of position, and holds the front of the gum in 
its original form. When the celluloid has moved to its 
place around the pins, drop cold water on it from a sponge 
in one hand, while holding the hot compress against it 
with the other. By this mode a tooth can be replaced 
without heating the plate, showing no sign of repair. 
A celluloid plate is damaged by being invested and heated 



FOR DENTAL PURPOSES. 99 

a second time, and it should not be done for so simple a 
repair as replacing a tooth, unless some part of the cellu- 
loid has chipped away — as, for instance, if a small piece 
is gone from the front of the socket (enough only to ex- 
pose the end of the root when in position), drop a little 
wax upon the vacant spot, after placing the tooth, and 
carve to the shape desired. "Without removing the wax, 
invest and mold as before described. The wax will pass 
off into the plaster, and its place will be supplied by the 
celluloid, of which there is usually enough to permit the 
flowing of the minute quantity required without damage. 
In this case it is necessary to heat the plate and use 
pressure. 

If there is a similar deficiency on the inside of the plate, 
exposing the pins of the tooth, drop wax into the vacancy, 
and proceed as before, except that in this case the wax is 
to be removed when the investment is made, and a piece 
of writing-paper or tin-foil should be placed just below the 
pins instead of over them, so as to force the flowing of 
the celluloid to cover them. 

Some prefer the following method of replacing a tooth : 
Heat the tooth selected for the case, and quickly press it 
into position, protecting the fingers with a napkin. Invest 
in plaster, covering the teeth and plate as shown in Fig. 
18. After the top is poured and hardened, separate and 
paint a light coating of plaster upon the part covering the 
repair. Place a piece of thin tin-foil over the exposed 
portion of the plate, and bring the sections of the flask 
together in the usual way. 

To remove a tooth from a celluloid plate, hold the out- 



100 VULCANITE AND CELLULOID 

side surface of the tooth to be removed in the flame of 
the lamp until the heat softens the celluloid around the 
pins slightly, when it may be taken off without trouble, 
and it will come away clean, without any of the celluloid 
adhering to the pins. Do not move the plate back and 
forth through the flame, or other teeth than the one 
desired may be loosened, or their perfect articulation may 
be interfered with. There is no danger of cracking the 
tooth so long as the flame does not come in contact with 
the pins. 

Vulcanite. 

Where the Eew-Mode Heater is used for vulcanizing, 
shrinkage or " creeping " of the rubber from the teeth is 
obviated. The plaster cast and investment, instead of 
being soft after vulcanization (as by the other methods), 
are hard. 

To Vulcanize Red Rubber. 

Make the cast and investment as in ordinary work. The 
flask may be heated and packed in the oven ; when this is 
completed, close the machine, and cover the screws for 
closing the flask with the caps, to make them absolutely 
steam-tight. Raise the steam-valve and admit the steam 
to the packing-chamber. After the heat has been raised 
to 320° F., allow the case to remain in the hot-box at that 
temperature one and a half hours. 

To Vulcanize Black Rubber. 
A pure jet-black rubber plate may be produced by 



FOR DENTAL PURPOSES. 101 

using perfectly pure black rubber and the dry process of 
vulcanization. The rubber should be absolutely free from 
coloring-matter, as this is only introduced to overcome 
the effect of the steam in bleaching it when vulcanized 
in the ordinary way. Dry out the cast and invest- 
ment thoroughly before inserting the rubber. See that 
no steam is allowed to enter the packing-chamber during 
the operation. The time required by the dry-heat method 
is five hours at 320° F., and the result is a brilliant jet- 
black piece of work, free from discoloration, which will 
not shrink or creep from the pins or teeth. The same 
directions are to be observed when vulcanizing red rubber 
by dry heat. 

New-Mode Continuous-Gum. 

To obtain the proper expression, each tooth should be 
available for placing in any position desired, instead of 
being arbitrarily held in association with others, as in a 
block. 

By using plain teeth, with rubber for the base and cel- 
luloid (which is well suited for the purpose) for the gum, 
an exquisite piece of work is made, which is called by the 
inventor the " New-Mode Continuous-Gum." It is easily 
the nearest approach to porcelain continuous-gum that 
has been attained with plastic materials. Its general 
adoption would do away with "bad joints" and broken 
blocks. It is the only rubber plate upon which a tooth 
may be replaced without re-vulcanization, and which after 
the repair is equal in strength and appearance to the 



102 



VULCANITE AND CELLULOID 



original piece ; and the only one upon which repairs can 
be repeated any number of times without injury to the 
original plate. This same style of work can also be done 
with gold and with cast-alloy plates. 



Directions for Making New-Mode Continuous-Gum. 

Using teeth made expressly for continuous-gum or cel- 
luloid work, set them up in wax in the usual manner, 
leaving the front or outside of the roots exposed. Cut a 
thin strip of the wax, warm it, and attach it to the upper 
edge of the portion of the wax plate representing the 

Fig. 26. 




gum, forming a rim which extends all around the 
outer margin. Finish the palatine surface to the form 
desired ; invest in the flask in the usual manner ; remove 
the wax; pack with rubber, and vulcanize. When re- 
moved from the flask the case will present the appearance 
shown in Fig. 26, the front or outside of the roots being 
exposed, and the narrow, undercut rim extending all 
around, leaving a space with retaining-grooves between 
the teeth for forming a gum of celluloid, looking very 
much as though the substance of the plate had been 



FOR DENTAL PURPOSES. 103 

gouged out for the purpose. The vulcanite plate is now 
completed, with the teeth firmly attached to it. 

To Put on the Celluloid Gum. 

Fill the groove with paraffine and wax, which should 
he melted and dropped on (this compound, not being 
sticky, does not adhere to the instrument, and is therefore 
more easily carved to the form desired) until all the space 
inside the rim, including the retaining-grooves between the 
necks of the teeth, is occupied. After the wax has hard- 
ened, which may he hastened by placing it in cold water, 
carve it into the desired form of gum. Make the wax 
smooth in the manner before described under " Directions 
for Preparing a Case for Celluloid." 

Invest the piece again in the following manner : Place 
the plate in one section of the flask with the teeth upward 
and raised at the front at a greater or lesser angle, as may 
be necessary, so that when the investment is completed 
the upper part of the flask may be removed without drag- 
ging. Imbed in plaster to the rim, pouring it over the 
palatine surface, covering the crowns, and taking care to 
fill the interstices between the necks of the teeth, but 
leaving their outer surfaces exposed. After the invest- 
ment sets, pour more plaster around the inner edge of 
the flask-ring, forming a ridge, leaving a groove or space 
between it and the plate. (See Fig. 27.) Complete the 
investment, and remove the wax from the groove and in- 
terstices between the roots of the teeth by pouring boiling 
water over it. Having selected a celluloid blank of proper 



104 VULCANITE AND CELLULOID 

size, saw off the outer rim (see Fig. 28); warm this 

Fig. 27. 



rim 




of celluloid in boiling water, and with the hand and 

Fig. 28. 



a 




cloth press it closely about the teeth, and hold it to its 



FOR DENTAL PURPOSES. 105 

place until stiff; it will then remain there until the 
two parts of the flask are entered upon the guide-pins. 
Join the two parts of the flask together, and place the in- 
vestment in the oven of the machine, having previously 
heated up the chamber. When the temperature of 280° F. 
is reached, the flask may be closed. As soon as this is 
accomplished, the case is ready to be removed from the 
oven and placed in a clamp to cool. 

When perfectly cold, remove the plate. The tin-foil 
will adhere to it, but it can be readily removed by insert- 

Fig. 29. 




ing the point of a knife under the edge and pulling it off, 
.leaving the surface of the celluloid gum as smooth and 
polished as that of the foil. 

A surface produced by the above method presents a 
smooth, polished gum ; but if the tin-foil is " stippled," as 
previously described, a striking resemblance to the natural 
membrane will be produced, the finished plate presenting 
the appearance shown in Fig. 29. The adjoining edges of 
the celluloid and rubber will be found perfectly united, 
each preserving its sharp outline. 

Fig. 30 is a palatal view of a finished celluloid case, 
showing the rugae as transferred from the model. 



106 



VULCANITE AND CELLULOID 



Celluloid Blanks. 

Five different series of plates are now made, each 
with from four to eight different sizes, giving a variety of 
thirty-three plates to select from, which will meet nearly 
every case. 

1. Ordinary uppers. — Eight sizes; smallest, Eo. 3, If 
inches x 2 wide, running up to E~o. 6J, 2J x 2f . The half 
numbers (3J-, 4J, etc.) are the same sizes as the even num- 
bers, but much heavier. 

2. "A" plates. — Same sizes and numbers as ordinary 
uppers, but double thickness, for cases where great absorp- 




tion has taken place. They are marked "A" on the upper 
surface. 

3. Lower plates. — Seven sizes; ETo. 1 J, smallest, to No. 4 J. 

4. Partial plates. — Three varieties, two sizes of each. 
Eos. 5 and 6 are for ordinary cases ; Eos. 7 and 8 are de- 
signed for cases where only the front teeth are to be re- 
placed ; E"os 9 and 10 are for the side teeth. 



FOR DENTAL PURPOSES. 107 

5. Plumper plates. — Four sizes, Nos. 3, 4, 5, and 6. These 
are nearly the same sizes as the ordinary uppers of the 
same numbers, but with very heavy rim, for cases where 
the gum is much absorbed. 

The "A" and "plumper" plates were principally de- 
signed for special cases ; dentists will find that they are 
very useful forms of plates, even for ordinary cases. The 
" A" plates of the larger sizes will afford material suffi- 
cient for any case that may present; the shape of the 
" plumper" plates, which are somewhat pointed in front, 
will adapt them to that class of mouths. Some of them 
also are high in the arch. 

The various partial plates will furnish material sufficient 
for any partial case. They can be readily adapted to any 
required form by cutting away any excess, which is done 
in a moment with a sharp knife, after softening the plate 
in boiling water. This is also the case with the "A" and 
" plumper" plates. 

Liquid Celluloid. 

This is made by cutting celluloid into pieces, and cover- 
ing it with spirits of camphor. To prevent evaporation, 
it should be kept in a tightly-stopped bottle. 

Final Directions to Celluloid Workers. 

Use good plaster, and do not mix it too thin ; select a 
plate which nearly fits the cast, with an excess in every 
part; turn the screws as soon as they will yield to the 
thumb and finger, and always gently ; follow up the rise 



108 VULCANITE AND CELLULOID. 

In temperature with increased pressure ; give the material 
plenty of time to flow between the turns ; increase the 
pressure toward the close of the molding; reduce the 
temperature of the piece at once after the completion of 
the molding, and keep the plate under pressure until it is 
stone cold. 



INDEX. 



Air-chambers 53 

Amalgam for repairing plates 57 

Amount of rubber required to fill the mold 27 

Arrangement of the teeth 18 

Articulating model 17 

the teeth against vulcanite 59 

Articulation for full upper and lower case. 17 

or taking of bite '. 15 

partial 38 

testing of. 20 

wax, length of. 15 

Automatic flask clamp 29 

Backings and metallic clasps 82 

Bite, full upper and lower 17 

taking of, for partial cases 38 

taking of, or articulation 15 

Black joints, to prevent 25 

vulcanite 4 35-100 

Bleaching vulcanite 52 

Bony ridges in the center of the mouth 38 

Breaking of the gums, to prevent 27 

teeth from the model, to prevent 14 

Broken tooth, to remove, from a celluloid plate 99 

to replace, on a celluloid plate 97 

Burnishing tin-foil to wax for celluloid 92 

Calcium sulphate 7 

Callipers 37 

Care of plates 82 

Carving celluloid, description of instruments 91 

Cast and investment, drying of. 94 

Casting the plaster mold 20 

Casts, metal 81 

plaster 14 

Caution 74 

Celluloid 67 

blanks 106 

burnishing tin-foil to the wax 92 

cooling and removing 73 

109 



110 



INDEX. 



Oelluloid, dark lines in 7g 

directions for preparing a case 90 

finishing 77 

flasking '., 57 

for repairing rubber plates 77 

gum, to attach, to a rubber plate 103 

hints on 77 

liquid 107 

machine and dental vulcanizer, New-Mode. 85 

molding 68 

molding in glycerin 72 

molding in lard or oil 73 

molding in the steam apparatus 69 

or rubber attachment 62 

plates, the forming of, before molding 80 

plates, the spring or warping of 77 

porous plates 78 

proper degree of heat for molding 89 

repairing 74 

size of the blank 80 

teeth, to remove from the plate 77 

the "Best" Hot Moist Air Apparatus 83 

waste gates for 68 

workers, final directions to 107 

working with the New-Mode Heater 89 

•Clasps, metallic, attached to vulcanite or celluloid 41-82 

•Cleanliness 82 

Closing the flask 28 

Coating the mold 24 

Collodion ; 24 

Coloring plaster for impressions 61 

Continuous-gum, New-Mode 101 

Cracking of thinly-ground gums, to prevent 27 

Dark joints, to prevent 25 

lines in celluloid 78 

Deep undercuts, to overcome 97 

Dentures, partial 38 

Description of celluloid blanks 106 

Detaching upper impressions 10 

Dies, metal « 81 

Directions for making New-Mode continuous-gum 1 02 

for preparing a case of celluloid 90 

for using the " Best " Moist Hot Air Celluloid Apparatus 88 



INDEX. Ill 

Directions to celluloid workers, final 107 

Dry heat, molding with 95 

Drying the cast and investment 94 

Elastic force of steam 30 

Final directions to celluloid workers 107 

Finishing celluloid , 77 

the vulcanite case 36 

Flange suction for lower plates 45 

Flask clamp, automatic 29 

closing of. 28 

opening of. 36 

Flasking celluloid 67 

plain teeth 21 

the case 20 

Foil, tin 24 

Forming of the celluloid plate before molding 80 

Full lower impressions 10 

lower plates with suction 45 

upper impressions 8 

Gates for the excess of celluloid 68 

for the excess of rubber 23 

Gauge for rubber 27 

Glycerin, molding celluloid in 72 

Gold or vulcanite plates, refitting, with a vulcanite lining 47 

Grinding teeth for partial cases 39 

Gum, celluloid, to put on rubber plates 103 

membrane, imitation of. 96 

Gutta-percha 5 

Hard or bony ridges, to overcome 38 

Have enough material 82 

Heating the rubber 26 

Heat, proper degree of, for molding celluloid 89 

Hints on celluloid 77 

Hot moist air, molding celluloid in 83 

Imitation of gum-membrane 96 

Impression and cast, separating of 14 

cup or tray, selection of 8 

Impressions, coloring the plaster for 61 

detaching upper 10 

full lower 10 

full upper 8 

in gutta-percha 5 

in modelling composition 7 



112 INDEX. 

Impressions in plaster of Paris : 7 

in wax q 

in wax and plaster 6 

of the mouth 5 

partial lower . 11 

partial, to remove 12 

partial upper 11 

position of patient when taking 9 

taking of, where there are loose teeth 11 

test for a good one , 9 

to remove partial lower 13 

varnish for 14 

varnishing 6 

Investment and cast, drying of 94 

Lard or oil for molding celluloid 73 

Length of the teeth 15 

of the wax articulation 15 

of time for vulcanizing 35 

Lines, dark, in celluloid plates 78 

Liquid celluloid 107 

rubber 58 

silex 24 

Loose teeth, to fasten 25 

Lower impressions, full 10 

partial 11 

partial, to remove 13 

Lower plates with suction 45 

Measure for rubber 28 

Metal casts 81 

Metallic clasps and backings 82 

clasps attached to vulcanite 41 

Mixing plaster 9-80 

Model, articulating 17 

Models, plaster 14 

Modelling composition 7 

Moist hot air for molding celluloid 83 

Molding celluloid 68 

celluloid in glycerin 72 

celluloid in hot moist air 83 

celluloid in the steam apparatus 69 

celluloid with dry heat 95 

Mold, coating of 24 

preparing, for rubber 22 



JNDEX. 113 

Mouths having soft places to overcome 53 

with bony ridges, to overcome 38 

Nausea, to overcome, while taking an impression 8 

New-Mode continuous-gum 101 

New-Mode Heater, Celluloid Machine, and Dental Vulcanizer 85 

Oil or lard for molding celluloid 73 

Opening the flask 36 

Packing for vulcanizers 61 

plates without pressure 39 

the case 25 

Partial dentures 38 

dentures, grinding teeth for 39 

impressions, to remove 12 

lower impressions 11 

lower impressions, to remove 13 

upper impressions 11 

Patient, position of, when taking an impression 9 

Pink vulcanite 35 

vulcanite, to bleach 52 

Plain teeth, flasking of 21 

Plaster and wax impressions 6 

Plaster casts or models 14 

coloring for impressions 61 

mixi ng of 9-80 

of Paris impressions 7 

quality of, for laboratory work 14-79 

soap solution for separating 60 

to hasten the setting of 10 

to prevent, running into the throat when taking an impression... 8 

varnish for 14 

Plate, care of 82 

celluloid, forming of, before molding... 80 

spring 59 

teeth for vulcanite work 42 

thickening of, in celluloid 82 

Polishing celluloid plates 77 

teeth 19 

the case 37 

Porcelain teeth attached to a metallic base with rubber or celluloid... 62 

teeth, to polish 19 

Porous plates, celluloid 78 

pi ates , v ulcani te 35 

Preparing a case for celluloid, directions for 90 

8 



114 INDEX. 

Preparing the mold for the rubber 22 

Preventing discolored j oints 25 

Ked vulcani te 100 

Refitting gold or vulcanite plates with vulcanite lining , 47 

Removal of partial impressions 12 

Removing and cooling celluloid 73 

Removing wax from the mold 23 

Repairing celluloid 74-97 

vulcanite >. 43-52 

vulcanite, a simple crack in 45 

vulcanite with amalgam 57 

vulcanite with celluloid 77 

vulcanite without pressure 44 

vulcanite with shellac 58 

vulcanite with Wood's fusible metal 58 

Replacing a broken tooth in celluloid 97 

Rubber, amount required to fill a mold 27 

liquid 58 

measure or gauge for , 28 

or celluloid attachment 62 

plate with celluloid gum 102 

to bleach 52 

Selecting the teeth 18 

Selection of impression cups 8 

Separating casts and impressions 14 

the flask 22 

Shellac for repairing vulcanite 58 

varnish 14 

Silex, liquid 24 

to thin , 24 

Silicate of soda 24 

Size of a celluloid blank 80 

Smoothing the wax 20 

Soap, solution of, for separating plates 60 

Softening the rubber 26 

Soft spots in mouths 53 

Spatula wax 17 

Spongy or porous plates. 35-78 

Springing of celluloid plates 77 

Spring plates 59 

Steam apparatus for molding celluloid 69 

Steam, elastic force of. 30 

Stippling to imitate gum-membrane 96 



INDEX. 115 

Suction plates, lower 45 

Sulphate of calcium 7 

Taking the articulation or bite 15 

Teeth , arrangement of 19 

articulating against rubber 59 

attached to a metal base with celluloid or rubber 62 

breaking from the model, to prevent 14 

length of. 15 

loose and elongated, taking an impression of 11 

loose, to fasten 25 

porcelain, polishing of 19 

selecting the 18 

Temperaments in regard to the teeth 18 

Test for a good impression 9 

Testing rubber 34 

the articulation 20 

The " Best " Hot Moist Air Celluloid Apparatus 83 

The New-Mode Heater, Celluloid Machine, and Dental Vulcanizer... 85 

Thermometers . 82 

Thickening of the plate 82 

Time occupied in reaching the vulcanizing point 34 

Tin-foil 24-92 

burnishing, to the wax for celluloid 92 

To construct a vulcanite plate without the usual scraping and polish- 
ing 53 

To make a new vulcanite plate and preserve the articulation of the 

old one 50 

Tooth, broken, to remove from a celluloid plate 99 

to replace a broken, in celluloid 97 

To put the celluloid on 103 

To remove a partial impression 12 

To remove celluloid teeth from the plate 77 

To remove teeth from a vulcanite base 57 

To repair vulcanite plates with Wood's fusible metal 58 

To take the warp out of a vulcanite plate 60 

To vulcanize black rubber 100 

To vulcanize red rubber 100 

Undercuts, deep, to overcome 97 

Upper impressions, detaching of 10 

impressions, full 8 

Yarnish, shellac, for impressions 14 

Vulcanite 5-100 

articulating the teeth against 59 



116 INDEX. 

Vulcanite, black ; .35-100 

liquid....' 58 

metal plate teeth for 42 

or gold plates refitted with vulcanite lining 47 

pink 85 

plates, to construct, without the usual scraping and polishing.... 53 

plate, to take the warp out of 60 

plate, with celluloid gum 102 

plate without pressure : 39 

repairing a cracked plate 52 

testing , 34 

to bleach 52 

to make a new plate and preserve the articulation of the old one 50 

to remove the teeth from 57 

to repair with amalgam 57 

to repair with shellac 58 

to repair with Wood's fusible metal 58 

Vulcanizers 31 

packing for 61 

Vulcanizing 30-100 

length of time for 35 

Warming the rubber 26 

Warp, to take out of a vulcanite plate 60 

Washing the wax from the mold 23 

Waste-gates 23 

for celluloid 68 

Wax and plaster impressions 6 

articulation, length of 15 

impression s 6 

spatula 17 

to make smooth 20 

Waxing up the case 19 

Welch's automatic flask-clamp 29 

Wood's fusible metal for repairing plates 58 

Working celluloid with the New-Mode Heater 89 



